Investigation into the increase in hay fever and eczema at age 16 observed between the 1958 and 1970 British birth cohorts.

OBJECTIVE: To investigate whether changes in certain perinatal and social factors explain the increased prevalence of hay fever and eczema among British adolescents between 1974 and 1986. DESIGN: Two prospective birth cohort studies. SETTING: England, Wales, and Scotland. SUBJECTS: 11,195 children born 3-9 March 1958 and 9387 born 5-11 April 1970. MAIN OUTCOME MEASURES: Parental reports of eczematous rashes and of hay fever or allergic rhinitis in the previous 12 months at age 16. RESULTS: The prevalence of the conditions over the 12 month period increased between 1974 and 1986 from 3.1% to 6.4% (prevalence ratio 2.04 (95% confidence interval 1.79 to 2.32)) for eczema and from 12.0% to 23.3% (prevalence ratio 1.93 (1.82 to 2.06)) for hay fever. Both conditions were more commonly reported among children of higher birth order and those who were breast fed for longer than 1 month. Eczema was more commonly reported among girls and hay fever among boys. The prevalence of hay fever decreased sharply between social classes I and V, increased with maternal age up to the early 30s, and was lower in children whose mothers smoked during pregnancy. Neither condition varied significantly with birth weight. When adjusted for these factors, the relative odds of hay fever (1986 v 1974) increased from 2.23 (2.05 to 2.43) to 2.40 (2.19 to 2.63). Similarly, the relative odds of eczema rose from 2.02 (1.73 to 2.36) to 2.14 (1.81 to 2.52). CONCLUSIONS: Taken together, changes between cohorts in sex, birth weight, birth order, maternal age, breast feeding, maternal smoking during pregnancy, and father''s social class at birth did not seem to explain any of the observed rise in the prevalence of hay fever and eczema. However, correlates of these factors which have changed over time may still underlie recent increases in allergic disease.     

Gastroschisis, low maternal age, and fetal morbidity outcomes

OBJECTIVE: To determine if the risk for fetal growth inhibition among gastroschisis-afflicted fetuses is heightened among younger gravidas (teen mothers). METHOD: This was a retrospective cohort study on live-born infants with isolated gastroschisis delivered in New York State from 1983 through 1999. We compared infants of mature (>20 years) mothers with those of younger (<20 years) mothers with respect to the following indices of fetal morbidity outcomes: low birth weight and very low birth weight, preterm and very pre-term, and small for gestational age. We used adjusted odds ratios to approximate relative risks. RESULTS: A total of 368 infants with isolated gastroschisis were analyzed. The two groups differed in terms of mean gestational age at delivery [Mean + standard deviation(SD) for infants with gastroschisis born to mature mothers = 37.2 weeks +/- 2.8 versus 36.3 weeks + 3.6 for those of teenage mothers(p = 0.01)], as well as mean birth weight [mean birth weight +/- SD for infants with gastroschisis born to mature mothers = 2562.4 grams +548.8 versus 2367.9 grams +/- 645.2 for those of younger mothers (p = 0.004)]. Infants of teen mothers were about twice as likely to be of low birth weight (OR = 1.70; 95% CI = 1.05-2.77) and about three times as likely to be born very preterm when compared to those of mature mothers (OR = 2.80; 95% Cl = 1.02-8.00). No significant differences were observed with respect to very low birth weight, pre-term and small for gestational age. CONCLUSION: Low maternal age appears to be a risk factor for low birth weight and very preterm birth among gastroschisis-affected fetuses. This information is potentially useful for planning by care providers and in counseling affected parents.     

Maternal diabetes: an independent risk factor for major cardiovascular malformations with increased mortality of affected infants.

BACKGROUND: Intensive medical care of women with diabetes has reduced their risks of bearing infants with congenital anomalies. To assess the preventive potential of preconceptional care, the data of a population-based study of cardiovascular malformations (CVM) were analyzed to determine the morphogenetic specificity of maternal diabetes risks, the morbidity and mortality of the infants, and maternal characteristics that might affect these risks. METHODS: The Baltimore-Washington Infant Study was a case-control study (1981-1989) that included all live born infants with confirmed CVM; control infants were a representative sample of the birth cohort. A questionnaire administered in home visits recorded parental information on social, medical, occupational, and environmental factors. For these analyses of preconceptional diabetes risks, the case group excluded chromosomal and mendelian disorders and was divided into 3 developmental categories and 12 diagnostic groups. RESULTS: Preconceptional maternal diabetes was strongly associated with CVM of early embryonic origin (odds ratio [OR] = 4.7, 95% confidence interval [CI] 2.8-7.9) and with cardiomyopathy (OR = 15.1, 95% CI 5.5-41.3), but not with obstructive and shunting defects (OR = 1.4, 95% CI 0.7-3.0). There was heterogeneity within these developmental categories: among laterality defects, diabetes was associated only with cardiovisceral and atrioventricular discordance (OR = 10.0, 95% CI 3.7-27.0); among outflow tract anomalies, the risk was strongly associated with normally related great arteries (OR = 6.6, 95% CI 3.2-13.3) but not with simple transpositions; and among atrioventricular septal defects, diabetes was associated with the complete but not with the partial forms (OR = 22.8, 95% CI 7.4-70.5). The association in early CVM was strongest among infants with multisystem, predominantly VACTERL, anomalies. All-cause mortality of infants with CVM was 39% among those with diabetic mothers and 17.8% in those with nondiabetic mothers. Deceased infants of diabetic mothers were also more likely to have extracardiac anomalies (P = 0.041), to be born prematurely (P = 0.007), and to have low birth weight (P = 0.011). Multivariate analyses of maternal factors revealed no significant confounders of the diabetes associations. CONCLUSIONS: The evidence of diabetes-induced major cardiac defects is of urgent clinical significance. The effectiveness of early preconceptional care in the prevention of congenital anomalies has been demonstrated repeatedly.     

Catch-up growth in females born short for gestational age reduces the risk of giving birth to short-for-gestational-age infants

OBJECTIVES: The aim of the present study was to study the effect of catch-up growth on the offspring's length at birth among females born short for gestational age. METHODS: Data of 1,363 females born short for gestational age (<-2 standard deviation scores) were obtained from the Swedish Birth Register. The females were included in the register both as babies and mothers. The effect of catch-up growth on the offspring's birth length was studied. RESULTS: Short adult stature was associated with a threefold increase in the risk of giving birth to a short infant [OR 3.08 (CI 1.73-5.50)] and smoking increased the risk in a dose-dependent manner. Overweight was associated with a reduced risk [OR 0.46 (CI 0.22-0.96)] of giving birth to a short infant. CONCLUSION: Catch-up growth to normal adult stature among women born short for gestational age is associated with a reduced risk of giving birth to a short-for-gestational-age infant.     

Adult height distribution in subjects born small for gestational age

The aim of the study was to investigate the post-natal growth of subjects born small for gestational age (SGA) by describing adult height distribution and by testing the effects of parental, neonatal and pregnancy-related parameters on the risk for adult short stature. The study population was made of adults selected on birth data from a maternity registry and born either small (SGA, n = 734, birth weight < 10th percentile) or appropriate for gestational age (AGA, n = 886, 25th < birth weight < 75th percentile) in whom anthropometric parameters were measured at 22 years of age. The SGA group demonstrated significantly reduced body size in comparison to the AGA group with a mean loss of 0.7 standard deviation (SD) in adult height. The frequency of adult short stature (< -2 SD) was 10.3% in the SGA group vs. 2.4% in the AGA group (p = 0.0001), adult height < -2.5 SD was observed in only 3.7% of the SGA group. Maternal (OR = 0.31 (0.16-0.62), p = 0.0001) and paternal (OR = 0.45 (0.31-0.67), p = 0.0001) heights and subjects birth length (OR = 0.78 (0.62-0.99), p = 0.04) significantly influenced the risk of adult short stature. In summary, post-natal growth defect remains moderate in the majority of subjects born SGA and < 4% only will end up with severe short stature requiring GH therapy according to most current recommendations. The role of parental height and birth length suggests that adult short stature in SGA subjects results at least in some cases from a familial and likely genetic growth disorder with antenatal onset.     

Risk of premature birth in multifetal pregnancy.

The risk of preterm delivery (< 37 weeks of gestation) is approximately nine times higher in women with multifetal pregnancies than in women with singleton pregnancies. However, it is possible that the risk will vary according to gestational week. To assess the risk of premature birth within 1 week by gestational age among multifetal pregnancies and compare the estimated risk with that of singleton pregnancies, we analyzed 6,036,475 infants born in singleton pregnancies and 90,887 infants born in multifetal pregnancies in Japan (> or =22 weeks) over the 5-year period 1989-1993. An estimate of the risk of birth within 1 week at gestational week n was obtained by dividing the number of infants delivered at gestational week n by the number of infants delivered at or beyond gestational week n. The risk at 22 weeks was 0.9 per 1000 fetuses for singleton pregnancies and 5.0 per 1000 for multifetal pregnancies. The risk remained relatively stable until 27 weeks of gestation, then sharply increased toward 36 weeks of gestation in both singleton and multifetal pregnancies. The odds ratio for birth within 1 week for fetuses of multifetal pregnancies compared with fetuses of singleton pregnancies was 5.9 (95% CI, 5.4-6.5) at 22 weeks of gestation, increasing gradually with increasing gestational age until 33 weeks of gestation (13.7; 95% CI, 13.1-14.2) but declining thereafter to 8.8 (95% CI, 8.6-8.9) at 36 weeks of gestation. Results of data analysis for each year of the 5-year period did not differ substantially.     

Separating parental and treatment contributions to perinatal health after fresh and frozen embryo transfer in assisted reproduction: A cohort study with within-sibship analysis

BackgroundCompared to naturally conceived children, adverse perinatal outcomes are more common among children born after assisted reproductive technology with fresh embryo transfer (fresh-ET) or frozen embryo transfer (frozen-ET). However, most previous studies could not adequately control for family confounding factors such as subfertility. We compared birth size and duration of pregnancy among infants born after fresh-ET or frozen-ET versus natural conception, using a within-sibship design to account for confounding by maternal factors.Methods and findingsThis registry-based cohort study with nationwide data from Denmark (1994–2014), Norway (1988–2015), and Sweden (1988–2015) consisted of 4,510,790 live-born singletons, 4,414,703 from natural conception, 78,095 from fresh-ET, and 17,990 from frozen-ET. We identified 33,056 offspring sibling groups with the same mother, conceived by at least 2 different conception methods. Outcomes were mean birthweight, small and large for gestational age, mean gestational age, preterm (<37 weeks, versus ≥37), and very preterm birth (<32 weeks, versus ≥32). Singletons born after fresh-ET had lower mean birthweight (−51 g, 95% CI −58 to −45, p < 0.001) and increased odds of small for gestational age (odds ratio [OR] 1.20, 95% CI 1.08 to 1.34, p < 0.001), while those born after frozen-ET had higher mean birthweight (82 g, 95% CI 70 to 94, p < 0.001) and increased odds of large for gestational age (OR 1.84, 95% CI 1.56 to 2.17, p < 0.001), compared to naturally conceived siblings. Conventional population analyses gave similar results. Compared to naturally conceived siblings, mean gestational age was lower after fresh-ET (−1.0 days, 95% CI −1.2 to −0.8, p < 0.001), but not after frozen-ET (0.3 days, 95% CI 0.0 to 0.6, p = 0.028). There were increased odds of preterm birth after fresh-ET (OR 1.27, 95% CI 1.17 to 1.37, p < 0.001), and in most models after frozen-ET, versus naturally conceived siblings, with somewhat stronger associations in population analyses. For very preterm birth, population analyses showed increased odds for both fresh-ET (OR 2.03, 95% CI 1.90 to 2.12, p < 0.001) and frozen-ET (OR 1.66, 95% CI 1.42 to 1.94, p < 0.001) compared with natural conception, but results were notably attenuated within siblings (OR 1.18, 95% CI 1.0 to 1.41, p = 0.059, and OR 0.92, 95% CI 0.67 to 1.27, p = 0.6, for fresh-ET and frozen-ET, respectively). Sensitivity analyses in full siblings, in siblings born within 3-year interval, by birth order, and restricting to single embryo transfers and blastocyst transfers were consistent with the main analyses. Main limitations were high proportions of missing data on maternal body mass index and smoking.ConclusionsWe found that infants conceived by fresh-ET had lower birthweight and increased odds of small for gestational age, and those conceived by frozen-ET had higher birthweight and increased odds of large for gestational age. Conception by either fresh-ET or frozen-ET was associated with increased odds of preterm birth. That these findings were observed within siblings, as well as in conventional multivariable population analyses, reduces the likelihood that they are explained by confounding or selection bias.Trial registrationClinicalTrials.gov ISRCTN11780826.

Kjersti Westvik-Johari and co-workers report on perinatal outcomes following fresh and frozen embryo transfer.     

A matched cohort comparison of the outcome of twin versus singleton pregnancies in Flanders, Belgium.

To compare perinatal outcome of singleton versus twin pregnancies a matched cohort study was performed in Flanders, Belgium. All twins delivered in the region of Flanders during 1998-1999 were compared to singletons, matched for gestational age, fetal sex and maternal parity, resulting in 4384 infants in each group. Above 32 weeks of gestation, birthweight was significantly lower in twins (2095 +/- 364 g versus 2315 +/- 523 g; p < 0.001, 95% confidence interval 193 to 246 g). Perinatal mortality was also significantly lower in twins (1.98% versus 1.26%; odds ratio for twins 0.63; 95% confidence interval 0.53-0.75; p < 0.001 ), this was mostly due to fetal and not to early neonatal mortality. Congenital malformations occurred less frequently in twins (2.5% versus 3.7%; odds ratio for twins 0.80, 95% confidence interval 0.69-0.92; p = 0.001). From gestational age of 32 weeks on, respiratory distress syndrome was less frequent in twins (6.7% versus 8.0%; odds ratio for twins 0.81; 95% confidence interval 0.68-0.97; p = 0.011 ). No significant differences were noted with regard to intraventricular haemorrhage, neonatal infections and retinopathy of prematurity. Although twins have a lower birthweight, their outcome is more favorable compared to singletons, when matched for gestational age.     

Plasmodium vivax Malaria in Pregnant Women in the Brazilian Amazon and the Risk Factors Associated with Prematurity and Low Birth Weight: A Descriptive Study

Introduction

Plasmodium vivax is the most prevalent malaria species in the American region. Brazil accounts for the higher number of the malaria cases reported in pregnant women in the Americas. This study aims to describe the characteristics of pregnant women with malaria in an endemic area of the Brazilian Amazon and the risk factors associated with prematurity and low birth weight (LBW).

Methods/Principal Findings

Between December 2005 and March 2008, 503 pregnant women with malaria that attended a tertiary health centre were enrolled and followed up until delivery and reported a total of 1016 malaria episodes. More than half of study women (54%) were between 20–29 years old, and almost a third were adolescents. The prevalence of anaemia at enrolment was 59%. Most women (286/503) reported more than one malaria episode and most malaria episodes (84.5%, 846/1001) were due to P. vivax infection. Among women with only P. vivax malaria, the risk of preterm birth and low birth weight decreased in multigravidae (OR, 0.36 [95% CI, 0.16–0.82]; p = 0.015 and OR 0.24 [95% CI, 0.10–0.58]; p = 0.001, respectively). The risk of preterm birth decreased with higher maternal age (OR 0.43 [95% CI, 0.19–0.95]; p = 0.037) and among those women who reported higher antenatal care (ANC) attendance (OR, 0.32 [95% CI, 0.15–0.70]; p = 0.005).

Conclusion

This study shows that P. vivax is the prevailing species among pregnant women with malaria in the region and shows that vivax clinical malaria may represent harmful consequences for the health of the mother and their offsprings particularly on specific groups such as adolescents, primigravidae and those women with lower ANC attendance.     

Maternal and Perinatal Outcomes of Twin Pregnancy in 23 Low- and Middle-Income Countries

Background

Twin pregnancies in low- and middle-income countries (LMICs) pose a high risk to mothers and newborns due to inherent biological risks and scarcity of health resources. We conducted a secondary analysis of the WHO Global Survey dataset to analyze maternal and perinatal outcomes in twin pregnancies and factors associated with perinatal morbidity and mortality in twins.

Methods

We examined maternal and neonatal characteristics in twin deliveries in 23 LMICs and conducted multi-level logistic regression to determine the association between twins and adverse maternal and perinatal outcomes.

Results

279,425 mothers gave birth to 276,187 (98.8%) singletons and 6,476 (1.2%) twins. Odds of severe adverse maternal outcomes (death, blood transfusion, ICU admission or hysterectomy) (AOR 1.85, 95% CI 1.60–2.14) and perinatal mortality (AOR 2.46, 95% CI 1.40–4.35) in twin pregnancies were higher, however early neonatal death (AOR 2.50, 95% CI 0.95–6.62) and stillbirth (AOR 1.22, 95% CI 0.58–2.57) did not reach significance. Amongst twins alone, maternal age <18, poor education and antenatal care, nulliparity, vaginal bleeding, non-cephalic presentations, birth weight discordance >15%, born second, preterm birth and low birthweight were associated with perinatal mortality. Marriage and caesarean section were protective.

Conclusions

Twin pregnancy is a significant risk factor for maternal and perinatal morbidity and mortality in low-resource settings; maternal risk and access to safe caesarean section may determine safest mode of delivery in LMICs. Improving obstetric care in twin pregnancies, particularly timely access to safe caesarean section, is required to reduce risk to mother and baby.     

Birth in winter can reduce the risk of lung cancer: A retrospective study of the birth season of patients with lung cancer in Beijing area,China

The season of birth is an important risk factor for several diseases. We explored the relationship between birth season and lung cancer. In this population-based retrospective study, we focused on patients with lung cancer who had registered at the Beijing Institute for Cancer Research from 2003 to 2012. In total, 33,025 patients were divided into five subgroups based on their histologic classification, and these five subgroups were compared with the general population (i.e., the permanent resident population of Beijing in 2013). A binary logistic regression method with sex and age as control factors was used to evaluate the relationship between birth season and lung cancer; P < 0.01 was statistically significant. Taking winter as a reference in our analysis of the relationship between season of birth and lung cancer, we found that people who were born in other seasons had a higher probability of developing lung cancer (spring: odds ratio [OR] = 1.06, 95% confidence interval [CI] = 1.03–1.09; summer: OR = 1.07, 95% CI = 1.04–1.10; autumn: OR = 1.06, 95% CI = 1.03–1.09) (P < 0.01). Among the five subgroups, persons with squamous cell carcinoma who were born in summer were more likely to develop lung cancer than those who were born in winter (OR = 1.09, 95% CI = 1.02–1.15, P = 0.006). The other subgroups showed no correlation with season of birth (P > 0.01). This study demonstrates that for people born in winter, the risks of developing lung cancer and squamous cell carcinoma are comparatively lower than those for people born in other seasons. Differences in immune function and the maternal nutrition status during pregnancy of people born in different seasons may explain this finding.     

Risk factors for heart disease associated with abnormal sidedness

BACKGROUND: The purpose of this study is to obtain information on potential familial and environmental risk factors for liveborn cases of heart disease associated with abnormal visceral and vascular sidedness, heterotaxy heart disease, so that hypotheses about this congenital cardiovascular malformation (CCVM) and its risk factors can be generated. We describe the characteristics of infants with heterotaxy heart malformations and case-control comparisons of interview data obtained on parental socio-demographic characteristics, occupational and household environmental exposures. METHODS: Cases and controls are drawn from the Baltimore Washington Infant Study (BWIS) a population based case control study of CCVM diagnosed in the region from 1981-89. RESULTS: Maternal diabetes (OR = 5.5, 95% CI = 1.6-19.1) and family history of malformations (OR = 5.1, 95% CI = 2.0-12.9) are strongly associated with cardiac disorders of sidedness. Cocaine use by mothers during the first trimester is associated with heterotaxy heart disease with odds of 3.7 (95% CI = 1.3-10.7). Cases of isolated dextrocardia shared risk factors with other heterotaxy malformations. The odds of a twin proband having heterotaxy heart disease is 4.8 (95% CI = 1.9-11.8) compared to singleton births. Twin probands are predominantly monozygotic twins in contrast to twin probands in other congenital cardiovascular malformations. CONCLUSIONS: Our findings are consistent with a role for multiple genetic factors in the development of left-right axis formation and with variable cardiac phenotypes according to gene expression and possible gene-environment interactions. Association with monozygotic twinning and with parental cocaine use may point to additional mechanistic clues for future research.     

Perinatal mortality in term and preterm twin and singleton births.

Although, in general, twins have higher perinatal mortality rates than singletons, preterm twins have lower perinatal mortality rates than singletons of the same birth weight or gestational age. This study investigated the hypotheses that this paradoxical twin advantage: 1) is due to gestational age distribution differences between the singleton and twin populations, and 2) is due to increased likelihood of birth having occurred in a tertiary perinatal center. A pre-existing, time-limited data set of all births in the province of Ontario in odd years between 1979 and 1985 was chosen for this study because of the large sample size (n = 618,579). Multivariable logistic regression of the relationship between perinatal mortality and twin status was controlled for mother's age, hospital level and gestational age. Findings confirm the lower mortality of preterm twins. After controlling for level of hospital of birth this difference remained, suggesting that level of hospital of birth was not a major factor responsible for the twin advantage. Analyses in which gestational age was standardized indicate that, for those whose gestational age was less than 2 SD below the mean for their particular group (twin or singleton), twins were actually at higher risk than singletons. These results support hypothesis 1 and do not strongly support hypothesis 2. The results also support earlier authors' suggestions that the definition of term birth should be different for twins and singletons     

Factors associated with initiation and exclusive breastfeeding at hospital discharge: late preterm compared to 37 week gestation mother and infant cohort

Background

To investigate and examine the factors associated with initiation of, and exclusive breastfeeding at hospital discharge of, late preterm (34 ^0/7 - 36 ^6/7 weeks) compared to 37 week gestation (37 ^0/7 - 37 ^6/7 week) mother and baby pairs.

Methods

A retrospective population-based cohort study using a Perinatal National Minimum Data Set and clinical medical records review, at the Royal Hobart Hospital, Tasmania, Australia in 2006.

Results

Late preterm and 37 week gestation infants had low rates of initiation of breastfeeding within one hour of birth, 31 (21.1%) and 61 (41.5%) respectively. After multiple regression analysis, late preterm infants were less likely to initiate breastfeeding within one hour of birth (OR 0.3 95% CI 0.1, 0.7 p = 0.009) and were less likely to be discharged exclusively breastfeeding from hospital (OR 0.4 95% CI 0.1, 1.0 p = 0.04) compared to 37 week gestation infants.

Conclusion

A late preterm birth is predictive of breastfeeding failure, with late preterm infants at greater risk of not initiating breastfeeding and/or exclusively breastfeeding at hospital discharge, compared with those infants born at 37 weeks gestation. Stratifying breastfeeding outcomes by gestational age groups may help to identify those sub-populations at greatest risk of premature cessation of breastfeeding.

     

Maternal age and non‐chromosomal birth defects,Atlanta—1968–2000: Teenager or thirty‐something,who is at risk?

OBJECTIVE: This investigation explored the association between maternal age and non-chromosomal birth defects to assess any increased risk associated with maternal age. METHODS: Birth defect cases were ascertained by the Metropolitan Atlanta Congenital Defects Program (MACDP), denominator information was obtained using birth certificate data. Infants with any chromosomal diagnosis were excluded. Effect estimates were calculated using 5-year maternal age categories with 25-29 years as the referent. Multiple logistic regression was used to adjust for maternal race, parity, infant sex, and birth year. RESULTS: A total of 1,050,616 singleton infants, born after > or = 20 weeks gestation in the five counties of metropolitan Atlanta from 1968 through 2000 who did not have a chromosomal abnormality and whose mother was 14 to 40 years old, were included in the analyses, 32,816 of them were identified with birth defects by the MACDP. Young maternal age (14-19 years) was associated with anencephaly (OR = 1.81, 95% CI = 1.30-2.52), hydrocephaly without neural tube defect (OR = 1.56, 95% CI = 1.23-1.96), all ear defects (OR = 1.28, 95% CI = 1.10-1.49), cleft lip (OR = 1.88, 95% CI = 1.30-2.73), female genital defects (OR = 1.57, 95% CI = 1.12-2.19), hydronephrosis (OR = 1.42, 95% CI = 1.11-1.82), polydactyly (OR = 1.29, 95% CI = 1.09-1.52), omphalocele (OR = 2.08, 95% CI = 1.39-3.12), and gastroschisis (OR = 7.18, 95% CI = 4.39-11.75). Advanced maternal age (35-40 years) was associated with all heart defects (OR = 1.12, 95% CI = 1.03-1.22), tricuspid atresia (OR = 1.24, 95% CI = 1.02-1.50), right outflow tract defects (OR = 1.28, 95% CI = 1.10-1.49), hypospadias 2nd degree or higher (OR = 1.85, 95% CI = 1.33-2.58), male genital defects excluding hypospadias (OR = 1.25, 95% CI = 1.08-1.45) and craniosynostosis (OR = 1.65, 95% CI = 1.18-2.30). CONCLUSIONS: Young and advanced maternal ages are associated with different types of birth defects. Underlying causes for these associations are not clear.     

Birth order,gestational age,and risk of delivery related perinatal death in twins: retrospective cohort study

ObjectiveTo determine whether twins born second are at increased risk of perinatal death because of complications during labour and delivery.DesignRetrospective cohort study.SettingScotland, 1992 and 1997.ParticipantsAll twin births at or after 24 weeks'' gestation, excluding twin pairs in which either twin died before labour or delivery or died during or after labour and delivery because of congenital abnormality, non-immune hydrops, or twin to twin transfusion syndrome.ResultsOverall, delivery related perinatal deaths were recorded for 23 first twins only and 23 second twins only of 1438 twin pairs born before 36 weeks (preterm) by means other than planned caesarean section (P>0.99). No deaths of first twins and nine deaths of second twins (P=0.004) were recorded among the 2436 twin pairs born at or after 36 weeks (term). Discordance between first and second twins differed significantly in preterm and term births (P=0.007). Seven of nine deaths of second twins at term were due to anoxia during the birth (2.9 (95% confidence interval 1.2 to 5.9) per 1000); five of these deaths were associated with mechanical problems with the second delivery following vaginal delivery of the first twin. No deaths were recorded among 454 second twins delivered at term by planned caesarean section.ConclusionsSecond twins born at term are at higher risk than first twins of death due to complications of delivery. Previous studies may not have shown an increased risk because of inadequate categorisation of deaths, lack of statistical power, inappropriate analyses, and pooling of data about preterm births and term births.

What is already known on this topic

It is difficult to assess the wellbeing of second twins during labourDeliveries of second twins are at increased risk of mechanical problems, such as cord prolapse and malpresentation, after vaginal delivery of first twinsIncreased risks of perinatal death in second twins have not been shown, but the methods of these studies were flawed

What this study adds

Second twins delivered at term are at increased risk of delivery related perinatal deathsIntrapartum anoxia caused 75% of these deaths in second twins, and most of these resulted from mechanical problems after vaginal delivery of first twinsPlanned caesarean section of twins at term may prevent perinatal deaths     

Low Birth Weight,Small for Gestational Age and Preterm Births before and after the Economic Collapse in Iceland: A Population Based Cohort Study

Objective

Infants born small for gestational age (SGA) or preterm have increased rates of perinatal morbidity and mortality. Stressful events have been suggested as potential contributors to preterm birth (PB) and low birth weight (LBW). We studied the effect of the 2008 economic collapse in Iceland on the risks of adverse birth outcomes.

Study design

The study population constituted all Icelandic women giving birth to live-born singletons from January 1^st 2006 to December 31^st 2009. LBW infants were defined as those weighing <2500 grams at birth, PB infants as those born before 37 weeks of gestation and SGA as those with a birth weight for gestational age more than 2 standard deviations (SD''s) below the mean according to the Swedish fetal growth curve. We used logistic regression analysis to estimate odds ratios [OR] and corresponding 95 percent confidence intervals [95% CI] of adverse birth outcomes by exposure to calendar time of the economic collapse, i.e. after October 6^th 2008.

Results

Compared to the preceding period, we observed an increased adjusted odds in LBW-deliveries following the collapse (aOR = 1.24, 95% CI [1.02, 1.52]), particularly among infants born to mothers younger than 25 years (aOR = 1.85, 95% CI [1.25, 2.72]) and not working mothers (aOR = 1.61, 95% CI [1.10, 2.35]). Similarly, we found a tendency towards higher incidence of SGA-births (aOR = 1.14, 95% CI [0.86, 1.51]) particularly among children born to mothers younger than 25 years (aOR = 1.87, 95% CI [1.09, 3.23]) and not working mothers (aOR = 1.86, 95% CI [1.09, 3.17]). No change in risk of PB was observed. The increase of LBW was most distinct 6–9 months after the collapse.

Conclusion

The results suggest an increase in risk of LBW shortly after the collapse of the Icelandic national economy. The increase in LBW seems to be driven by reduced fetal growth rate rather than shorter gestation.     

Genetic polymorphisms for vascular endothelial growth factor in perinatal complications

Low birth weight (LBW) infants have increased susceptibility to perinatal complications. An immature and impaired vascular system may possibly participate in these complications. There is evidence that supports the notion that vascular endothelial growth factor (VEGF), which is an essential regulator of embryonic angiogenesis, plays a central role in the pathogenesis of perinatal complications. We aimed to test whether functional genetic polymorphisms of VEGF are associated with the risk of preterm birth or perinatal morbidity. We enrolled 128 LBW infants (< or = 1500 grams). VEGF T-460C, VEGF C-2578A and VEGF G+405C polymorphisms were determined by real-time PCR or PCR-RFLP, respectively. Their genotypes were compared with VEGF genotypes of 200 healthy, term neonates. The prevalence of the VEGF+405 C allele was higher in LBW infants than in healthy, term neonates (OR [95% CI]: 1.29 [1.01-1.65]). Carrier state for the VEGF -2578A allele was an independent risk factor for enterocolitis necrotisans (NEC) (adjusted OR [95% CI]: 2.77 [1.00-7.65]). The carrier state for the VEGF -2578AA genotype was associated with a decreased risk of acute renal failure (ARF) (adjusted OR [95% CI]: 0.2 [0.05-0.78]). These results suggest that VEGF G+405C polymorphism might be associated with a higher risk of preterm birth and that VEGF C-2578A polymorphism may participate in the development of perinatal complications such as NEC and ARF.     

Risk for gastroschisis in primigravidity, length of sexual cohabitation, and change in paternity

BACKGROUND: Maternal epidemiologic similarities between gastroschisis and preeclampsia have led to the objective of evaluating the risk for gastroschisis related to primigravidity, change in paternity, and length of cohabitation, considered as risk factors for preeclampsia. METHODS: The subjects were 288 newborns with isolated gastroschisis and 576 normal controls, matched by maternal age. They were ascertained in the Estudio Colaborativo Latino Americano de Malformaciones Congenitas hospital network of 10 South American countries between 1982 and 2005. Epidemiologic variables were compared among controls, between primigravidas and multigravidas, between multigravidas who had and had not changed partners, and between mothers with short and long cohabitation times with their partners. Risks associated with primigravidity, short cohabitation time, and changing paternity, as well as their combinations, were calculated. An eventual interaction between maternal age and the three risk factors was assessed. RESULTS: Only a short cohabitation time showed a significant OR for gastroschisis (OR = 2.36, 95% CI: 1.52-3.66, p < .001), whereas ORs were not significant for primigravidity (OR = 1.40, 95% CI: 0.84-2.35, p = .192) nor for changing paternity (OR = 1.20, 95% CI: 0.49-3.10, p = .752). The risk was highest for multigravidas who had changed partners (OR = 8.71, 95% CI: 2.93-21.12, p < .001), followed by multigravidas who had not changed partners (OR = 3.99, 95% CI: 1.07-15.43, p = .049), and by primigravidas (OR = 3.02, 95% CI: 1.58-5.76, p = .001), all having cohabitated for a short time. Maternal age did not modify these risks. CONCLUSIONS: Three groups at risk for a child with gastroschisis were identified, all having in common a short cohabitation time. Antigenic or "modern" lifestyle-related factors might be involved in the origin of gastroschisis.     

Etiology of individual differences in birth weight of twins as a function of maternal smoking during pregnancy.

Birth weight is in large extent influenced by gestational age. In addition genetic and environmental factors determine intrauterine growth and birth weight. The contributions of these factors may be influenced by maternal smoking during pregnancy. We examined birth weight and maternal smoking in a sample of 2930 twin pairs from the Netherlands Twin Register using structural equation modelling. Gestational age accounted for 27-44% of the variance in birth weight. A lower variability of birth weight and a lower association of birth weight with gestational age was found in twins whose mothers smoked during pregnancy. The variance not associated with gestational age was independent of maternal smoking during pregnancy. A systematic smaller part of the variability in birth weight was associated with variability in gestational age in second born twins compared to first born twins. The heritability of interindividual differences in birth weight was modest (10% for twins with non-smoking mothers and 11% for twins with smoking mothers). Common environmental influences other than gestational age accounted for a slightly larger part of the variance not associated with gestational age (17-20%).