Maternal parity affects neonatal survival rate in a colony of captive bred baboons (Papio hamadryas)

Background Non‐human primates, particularly baboons, are valuable as animal models for reproductive research, because of their similarity to humans. Knowledge of colony‐specific pregnancy and neonatal outcomes is essential for interpretation of such research. Methods A retrospective review of the reproductive records of the Australian National Baboon Colony (ANBC) from 1994 to 2006 was performed. Results The overall live birth rate was over 70% of recognized pregnancies. Pregnancy loss was due to equal proportions of spontaneous abortion and stillbirth, and was not affected by maternal age or parity. Stillbirth rates were increased by the use of animals in novel late pregnancy experimental protocols. Neonatal mortality rates were low overall, but significantly higher in primiparous compared with multiparous mothers (P < 0.05). There were no cases of maternal mortality. Conclusions The success of the ANBC breeding programme is demonstrated by the low rate of pregnancy loss, high neonatal survival rate and lack of maternal mortality.     

The baboon model (Papio hamadryas) of fetal loss: maternal weight,age, reproductive history and pregnancy outcome

Background Several risk factors are associated with the incidence of human stillbirths. The prevention of stillbirths in women is a pressing clinical problem. Methods We reviewed 402 pathology records of fetal loss occurring in a large baboon (Papio spp.) colony during a 15‐year period. Clinical histories of 565 female baboons with one or more fetal losses during a 20‐year period were analyzed for weight, age, and reproductive history. Results Fetal loss was most common at term (35.57%) and preterm (28.61%) and less common in the first half of gestation (11.20%) and post‐term (5.22%). Greater maternal weight, older age, history of stillbirth and higher parity were independent predictors for stillbirth. An exponential increase in the incidence of fetal loss was observed beginning at age 14 years in baboons. Conclusions Fetal loss and maternal risk factors associated with stillbirths in baboons were similar to those documented in women.     

Factors affecting frozen and fresh embryo transfer pregnancy rates in cattle.

The effects of a large number of factors on the pregnancy rates of fresh and frozen cattle embryos were examined over a period of years at several different locations. For fresh embryos, overall pregnancy rates were 68.3% (n=9023) and 77.1% (n=2650) at different locations and time periods. Frozen-thawed embryo pregnancy rates were 56.1% (n=3616) in The Netherlands and 58.4% (n=5297) and 68.7% (n=774) for two studies in the United States. Pregnancy rates of surgical versus nonsurgical transfers were very similar. There were no differences in the pregnancy rates of beef versus dairy embryos, but the pregnancy rate was higher in dairy and beef heifers and beef cows than in dairy cows. Although on-farm pregnancy rates in California were higher than in the northeast United States, there was no influence of season on pregnancy rate. Estrous asynchrony between plus and minus 24 h did not affect pregnancy rate for frozen-thawed or fresh embryos. Neither breed nor parity of recipients affected the influence of asynchrony on pregnancy rates. Embryo grade was a significant factor in pregnancy rate for both fresh and frozen-thawed embryos, but neither embryo stage nor age was a significant factor. Pregnancy rate was not affected by holding embryos after flushing for up to 3 h prior to freezing.     

Reproductive Parameters and Maternal Investment in Mandrills (Mandrillus sphinx)

We report on 14 years of reproductive data for semifree-ranging mandrills (Mandrillus sphinx) in Gabon, and we explore relationships between female rank, age and parity, and reproductive strategies. Most births (61% of 132) occurred during the wet season in Gabon, between January and March. Female rank and parity were unrelated to the timing of parturition. Gestation lengths average 175 days (SE = ±1 day; N = 61) and were similar irrespective of female rank, parity, or sex of offspring. Birth sex ratio did not differ significantly from unity (52% male), and was unrelated to maternal rank or parity. Stillbirths and neonatal mortality tended to be more common among lower-ranking females than among either mid-ranking or dominant females. Median age at first birth is 4.71 years, at a median body mass of 7.6 kg, ca 5 years before females attain their adult body mass (median 12 kg). Age at first reproduction is significantly correlated with dominance rank, with dominant females giving birth on average 1.3 years earlier than lower-ranking females do. Interbirth intervals (IBI) average 405 days (range 184–1159 days, N = 103), and are independent of the sex of the offspring. Infant death within 6 months shortened IBI to 305 days. Increasing age and parity are also associated with short IBI, as is higher rank. Maternal rank and parity appear to influence reproductive success in female mandrills, but there is no apparent differential maternal investment by sex.     

Population based study of rates of multiple pregnancies in Denmark, 1980-94.

OBJECTIVE: To study trends in multiple pregnancies not explained by changes in maternal age and parity patterns. DESIGN: Trends in population based figures for multiple pregnancies in Denmark studied from complete national records on parity history and vital status. POPULATION: 497,979 Danish women and 803,019 pregnancies, 1980-94. MAIN OUTCOME MEASURES: National rates of multiple pregnancies, infant mortality, and stillbirths controlled for maternal age and parity. Special emphasis on primiparous women > or = 30 years of age, who are most likely to undergo fertility treatment. RESULTS: The national incidence of multiple pregnancies increased 1.7-fold during 1980-94, the increase primarily in 1989-94 and almost exclusively in primiparous women aged > or = 30 years, for whom the adjusted population based twinning rate increased 2.7-fold and the triplet rate 9.1-fold. During 1989-94, the adjusted yearly increase in multiple pregnancies for these women was 19% (95% confidence interval 16% to 21%) and in dizygotic twin pregnancies 25% (21% to 28%). The proportion of multiple births among infant deaths in primiparous women > or = 30 years increased from 11.5% to 26.9% during the study period. The total infant mortality, however, did not increase for these women because of a simultaneous significant decrease in infant mortality among singletons. CONCLUSIONS: A relatively small group of women has drastically changed the overall national rates of multiple pregnancies. The introduction of new treatments to enhance fertility has probably caused these changes and has also affected the otherwise decreasing trend in infant mortality. Consequently, the resources, both economical and otherwise, associated with these treatments go well beyond those invested in specific fertility enhancing treatments.     

Natural selection and reproductive behavior in Italy, 1930-1993

We studied the relaxation of natural selection affecting the newborn population in Italy between 1930 and 1993 due to the decrease in the stillbirth (mortality) rate and the simultaneous changes in women's reproductive behavior (strategies). Results show that, apart from a drastic overall reduction, the stillbirth rate has varied among different groups of neonates. The present stillbirth rate of less than 5 per thousand, observed in 8 of the 20 phenotypic classes defined on the basis of maternal age at delivery and neonate birth order, most likely represents an unavoidable biological or genetic cost. A 9 per thousand stillbirth rate, about twice the potential minimum, exists among neonates born to women delivering at advanced age (> or = 35): the risk they face at the first or, in adverse living conditions, the fourth pregnancy could, however, be decreased by a policy aimed at countering the tendency to delay maternity and improving antenatal care in economically disadvantaged areas of the country.     

Relationship of parity and body condition score to pregnancy rates in Florida beef cattle

Pregnancy rates, determined by per rectum palpation, were analyzed with respect to cow parity (range 1 to >8 calvings) and body condition score (BCS, 1=thin to 9=fat) at pregnancy examination for 3734 beef cattle females on 3 commercial beef operations (8 herds) in 3 Florida counties in 1989 and 1990. The means and standard deviations for the herds were the following: pregnancy rate, 81.3 +/- 39% (range 62.1 to 91.5%); BCS, 4.7 +/- 0.6 (range 4.3 to 4.9); and parity, 3.9 +/- 2.3 (range 2.8 to 4.8). Significant associations were found between pregnancy rate, parity, BCS and herd (P < 0.001); and between the variable interactions, parity with BCS, herd with BCS, and herd with parity (P < 0.001). Cows with a BCS /=5 had a pregnancy rate of 90%. Cows having a parity of <4 had a PR of 80%, while cows having a parity >/=4 had a PR of 85%. The interaction of parity with BCS was significant, resulting in pregnancy rates as follows; parity <4 and BCS /= 5 was 88%; parity >/=4 and BCS /=5 and BCS >/= 5 was 93%. Body condition, parity, and the interaction of body condition and parity play important roles in the reproductive performance of commercial beef cows in Florida.     

Characteristic features of the reproduction of Koshima monkeys,Macaca fuscata fuscata: A summary of thirty-four years of observation

The reproductive data for Japanese monkeys,Macaca fuscata fuscata, which had been recorded for the 34 years from 1952 to 1986 on Koshima, were analyzed in terms of the influence of changes in artificial food supplies, the differences in reproductive success between females, the timing of births, and the secondary sex ratio. Koshima monkeys increased in number until 1971 when the population density was still small and artificial provisioning was copious. As described byMori (1979b), the severe reduction in artificial food supplies, which began in 1972, had an enormous deleterious effect on reproduction: the birth ratio of adult females of 5 years of age or more fell from 57% to 25%; the rate of infant mortality within 1 year of birth rose from 19% to 45%; primiparous age rose from 6 to 9 years old on average; and there was an increased death rate among adult and juvenile females. The prolonged influence of “starvation” may be seen in the significantly delayed first births of those females that were born just before the change in food supplies. When reproductive parameters are compared between the females who belonged to six lineages in the group during these periods, they were found to be rather consistent, although some individual differences can be recognized among females and subgroups. The apparent trend was that some of the most dominant females retained superior reproductive success while that of the second-ranked females has tended to diminish over the years since 1972. Such opposing trends were seen only in the most dominant lineage group and such a difference was not recognized among the females of other lineages. The difference in reproductive success is discussed in relation to both the different situations that arise because of the artificial food supplies and differences in feeding strategies. Multiparous females, after a sterile year, gave birth somewhat earlier than those who reared infants in the preceding year and, when artificial provisioning was intense, they tended to give birth a little earlier than during other periods. There is some evidence that the mortality of later-born infants was higher than that of earlier-born infants after 1972. However, this difference may not be responsible for the differential reproductive success of females since the timing of births did not differ among lineages. Furthermore, during the time when many females gave birth continuously, prior to 1972, the infant mortality did not differ with respect to the timing of births. The differences in infant mortality were not correlated with the reproductive history, parity or age of the mother, or with the sex of the infant. The secondary sex ratio varied by only a small amount, from slightly male-biased ratio (114: 100) when correlated with reproductive history, parity, age of mother, sex and survival ratio for preceding infants, timing of birth, and lineage of the female. Furthermore, the change in artificial food supplies did not cause any modifications of the secondary sex ratios, despite its enormous deleterious effect on reproduction. The secondary sex ratio of Japanese monkeys may not be influenced by the social factors mentioned.     

Sex ratio and mortality in a laboratory colony of the common marmoset (Callithrix jacchus).

In a retrospective study sex ratio and mortality were analysed in a captive colony of common marmosets (Callithrix jacchus). Seven hundred and thirty-five infants in 294 litters (20 singletons, 119 twins, 140 triplets, 14 quadruplets) out of 57 breeding females were evaluated. The sex ratio at birth was 0.95 males:1.0 females. The frequency of males and females, as well as the sex composition of twins and triplets confirm the assumption of dizygotic twinning in the common marmoset. According to age at death, 9 categories were differentiated, with perinatal mortality being the highest. Once early infancy had passed the probability of a common marmoset infant of our colony reaching childhood is nearly 95%. Sixty per cent of all liveborn infants survived beyond 18 months. Mortality of infants at birth from primiparous mothers did not differ from that of pluriparous females, nor did the survival rate of infants with the filial generation the respective female had reached (F1 to F6). Females with a high ratio of triplets and quadruplets had a lower reproductive success than females with a majority of singleton or twin deliveries. Differential mortality between males and females was not observed. The frequency of stillbirths was not strongly related to parity, but was to litter-size. Most stillborn babies were seen in sets of quadruplets, most abortions in singletons. A normal socialization in a stable social environment, as well as not pairing the animals before they are fully adult, are considered important factors in good breeding success and infant survival.     

The placental growth factor (PGF) – a positional and functional candidate gene influencing calving ease and stillbirth in German dairy cattle

The bovine placental growth factor‐encoding gene (PGF) was analysed as a positional and functional candidate gene for the maternal effect on stillbirth and calving ease in first parity. Prominent levels of PGF expression have been reported for the whole human placenta and umbilical vein endothelial cells. Modulation of angiogenesis, vessel remodelling and vascular permeability during implantation and placentation suggest an influence on trophoblast function during pregnancy. Changes of expression or protein function may therefore be crucial to pregnancy and parturition. By comparative sequencing of bulls with extreme approximate daughter yield deviations for calving traits, we identified 37 SNPs and two insertions/deletions within the PGF gene. Seventeen of the identified polymorphisms were genotyped in 368 selected bulls and tested for association with approximate daughter yield deviations for calving traits. In a single marker analysis, all SNPs were significantly associated with maternal stillbirth and calving ease first parity. The allele substitutions of the significant SNPs explain 8% to 14% and 8% to 15% of the additive genetic variance for maternal stillbirth and maternal calving ease first parity, respectively. There is no evidence that any of the polymorphisms identified within this study could be the causal mutation underlying the QTL, which is likely to be a regulatory mutation. In summary, we report polymorphisms in the bovine PGF gene significantly associated with the maternal effect on stillbirth and calving ease in animals under selection. These results should be confirmed and extended in further studies to identify the causal mutation underlying the QTL analysed.     

Prosimian juvenile mortality in zoos and primate centers

I review literature on juvenile mortality of captive prosimians in order to evaluate the available information on captive breeding. Juvenile mortality includes abortion, premature mortality, stillbirth, and death of the unweaned young. Prosimian juvenile mortality ranges between 25 and 45% in captive populations. It is generally lower in the Lemuroidea, particularly the Cheirogaleidae, than in the Lorisoidea. Mortality is particularly high in the Lorisinae. Most mortality, including a high stillbirth rate, occurs on the first day and during the first 10 days thereafter. Stress, maternal neglect and traumatic insults, not infrequently linked to each other, are the most frequently reported causes of death. The percentage of congenital malformations tends to be high in some colonies. Sex of the infant and parity seem to be important risk factors for juvenile mortality, whereas litter size does not appear to be important. Based on few data, wild- caught females appear to have higher breeding success than those born in captivity. Synchronized births in lemuroids and isolated births in Galagoare more likely to result in successfully weaned infants.     

Reproductive health among married and unmarried mothers aged less than 18, 18–19, and 20–24 years in the United States, 2014–2019: A population-based cross-sectional study

BackgroundStudies in low- and middle-income regions suggest that child marriage (<18 years) is a risk factor for poor reproductive outcomes among women. However, in high-income-country contexts where childbearing before age 18 occurs predominantly outside marriage, it is unknown whether marriage is adversely associated with reproductive health among mothers below age 18. This study examined the joint associations of marriage and adolescent maternal age group (<18, 18–19, and 20–24 years) with reproductive, maternal, and infant health indicators in the United States.Methods and findingsBirth registrations with US resident mothers aged ≤24 years with complete information on marital status were drawn from the 2014 to 2019 Natality Public Use Files (n = 5,669,824). Odds ratios for the interaction between marital status and maternal age group were estimated using multivariable logistic regression, adjusting for covariates such as maternal race/ethnicity and nativity status, federal program participation, and paternal age. Marriage prevalence was 3.6%, 13.2%, and 34.1% among births to mothers aged <18, 18–19, and 20–24 years, respectively. Age gradients in the adjusted odds ratios (AORs) were present for most indicators, and many gradients differed by marital status. Among births to mothers aged <18 years, marriage was associated with greater adjusted odds of prior pregnancy termination (AOR 1.64, 95% CI 1.52–1.77, p < 0.001), repeat birth (AOR 2.84, 95% CI 2.68–3.00, p < 0.001), maternal smoking (AOR 1.24, 95% CI 1.15–1.35, p < 0.001), and infant morbidity (AOR 1.07, 95% CI 1.01–1.14, p = 0.03), but weaker or reverse associations existed among births to older mothers. For all maternal age groups, marriage was associated with lower adjusted odds of late or no prenatal care initiation, sexually transmitted infection, and no breastfeeding at hospital discharge, but these beneficial associations were weaker among births to mothers aged <18 and 18–19 years. Limitations of the study include its cross-sectional nature and lack of information on marriage timing relative to prior pregnancy events.ConclusionsMarriage among mothers below age 18 is associated with both adverse and favorable reproductive, maternal, and infant health indicators. Heterogeneity exists in the relationship between marriage and reproductive health across adolescent maternal age groups, suggesting girl child marriages must be examined separately from marriages at older ages.

In a population-based study, Andrée-Anne Fafard St-Germain and colleagues examine the joint associations of marriage and adolescent maternal age group (<18, 18-19, and 20-24 years) with reproductive, maternal, and infant health indicators in the United States.     

Maternal and neonatal factors influencing premature birth and low birth weight in Australia

This study identified the influences of neonatal and maternal factors on premature birth and low birth weight in New South Wales, Australia. Bivariate and multivariate analyses were used to explore the association of selected neonatal and maternal characteristics with premature birth and low birth weight. The findings of this study showed that premature birth and low birth weight rate significantly varied by infant sex, maternal age, marital status, Aboriginality, parity, maternal smoking behaviour during pregnancy and maternal hypertension. First-born infants, and infants born to mothers aged less than 20 years, or who were single, separated/divorced, Aboriginal or who smoked during the pregnancy, were at increased risk of being premature or of low birth weight. This study also found that risk factors for premature births and low birth weight were similar in both singleton and multiple births. Gestational age was confirmed to be the single most important risk factor for low birth weight. The findings of this study suggest that in order to reduce the incidence of low birth weight and premature births, health improvement strategies should focus on anti-smoking campaigns during pregnancy and other healthcare programmes targeted at the socially disadvantaged populations identified in the study.     

Influence of maternal age, parity and social class on perinatal mortality in Scotland: 1960-82

This study examines secular changes in the influence of maternal age, parity and social class on perinatal mortality in Scotland. Using cross-sectional national data on all Scottish legitimate births the effects of these factors are estimated on the risk of stillbirths, neonatal and perinatal deaths, and the extent to which the current pattern of relative risks in the early 1980s has changed over the past 2 decades is investigated. Social class is used as a crude measure of relative as opposed to absolute differences in socioeconomic conditions which may influence reproductive outcomes. The effects of age, parity and social class are estimated using logistic models. The most parsimonious model adequately describing the data is provided by a main effects model without interactions. Despite changes in reproductive behavior, improved access to maternity services and more effective perinatal care, the influence of maternal age and social class on perinatal mortality remained unchanged between 1960 and 1982. Although the absolute risks of stillbirths and neonatal deaths declined in all maternal age groups, this improvement was not accompained by a significant change in the relative risks traditionally associated with age. Despite no significant changes in the traditional J-shaped association between parity and stillbirths, cross-sectional analysis shows that in the early 1980s the risk of both neonatal and perinatal deaths decreased as parity increased. This finding is consistent with the pattern of risks observed in longitudinal studies and retrospective surveys of reproductive histories. In view of the stability of age, parity and social class effects on the risk of perinatal mortality, little if any of the overall decrease in Scottish stillbirth and neonatal death rates can be attributed to a significant narrowing of relative risks. The results suggest that the attributable risk of high maternal age or low social class on perinatal mortality is negligible. Future improvements in perinatal mortality are thus likely to result from a continuation of the uniform decrease in perinatal mortality for women of all ages, parities and social classes and not from a diminishing of differences in relative risks which are now virtually identical for a large and growing % of women in Scotland.     

Congenital malformations and variations in reproductive performance in the ferret: effects of maternal age, color and parity

Demographic data of ferrets from a commercial breeding colony were analyzed for the effects of maternal age, parity and strain on reproductive performance and the frequency of gross congenital abnormalities observed at parturition. Litter size (mean +/- SEM) was found to be greatest for young, primiparous females (10.3 +/- 0.2) and decreased with advancing maternal age and parity to a cohort mean of 8.1 +/- 0.1 for third parity females 16 months of age. Age, parity or strain had no effect on 24-hour neonatal mortality (7%) or mortality from birth to weaning (20%) and an examination of the causes for death suggested that these rates can be reduced. The malformation rate from two cohorts of females whelping at different times of the year was low (less than 1.0%) and not significantly different. A higher frequency of malformed offspring was detected in females of low previous parity (0-2) than in those with three or more. Based on data obtained in this survey, the ferret would seem a valuable alternative, nonrodent species for teratologic investigations using currently recommended protocols.     

神农架川金丝猴投食群的母婴关系

灵长类动物母亲的育婴行为不仅对后代的存活起着关键作用,而且对婴猴的发育和成年后的社会交往有着重大影响,因此母-婴关系一直是灵长类学研究的热点之一。为了解川金丝猴的母-婴关系,探讨川金丝猴母-婴关系个体差异的影响因素,我们于2013年3月至2014年10月,以母-婴间相对距离表示照料强度,对神农架川金丝猴的母-婴照料关系以及母亲照料强度个体差异的影响因素进行了定量研究。结果表明：母亲照料行为强度、母亲对阿姨行为的容忍与婴猴年龄相关,限制行为与婴猴年龄不相关。身体接触与婴猴年龄不相关;腹部接触以及母-婴相对距离小于1 m与婴猴年龄呈负相关;相对距离1 m至5 m、相对距离5 m至10 m和相对距离大于10 m与婴猴年龄呈正相关;母亲对阿姨行为的拒绝与婴猴年龄呈负相关;母亲对婴猴的限制行为与年龄不相关。总的来说,即随着婴猴成长,母婴间距离越来越远,母亲也逐渐减少对婴猴的保护。母亲的生育经验、婴猴性别、婴猴出生先后和社会单元大小对神农架川金丝猴母婴关系没有显著影响,补食群丰富的食物资源和群内雌性友好的关系可能是导致本结果的原因。     

An evolutionary perspective on the patterning of maternal investment in pregnancy

Pregnancy is thought to be a metabolically very expensive endeavor, yet investigations have produced inconsistent results concerning the responsiveness of human birth weight to maternal nutritional stress or nutritional intervention. These findings have led some researchers to conclude that fetal growth is strongly buffered against fluctuations in maternal energy balance, making the fetus in effect a “nearly perfect parasite.” This buffering would appear to be a reasonable adaptive response given the high risk of morbidity and mortality associated with low birth weight. However, a life-history approach leads to the prediction that maternal investment strategies in pregnancy should be geared toward maximizing lifetime reproductive success rather than simply the success of the current pregnancy, and by extension that maternal investment strategies should vary with reproductive value. The physiology of human pregnancy in fact appears to include a number of mechanisms that protect maternal energy resources from diversion to the fetus and preserve them for future reproductive events. These mechanisms include adjustment of blood flow to the uterus and perhaps minor adjustments in gestation length, although evidence for the latter is scant. Suggestions are made for ways of investigating these maternal options.     

Contraceptive practices and fertility among Southeast Asian, black, and white mothers attending a maternal infant care program

The purpose of this analysis was to determine if there were differences in selected fertility characteristics including parity, pregnancy spacing, age at 1st pregnancy, age of menarche, breastfeeding postpartum, and contraceptive practices among white, black, Hmong, and other Southeast Asian mothers attending a maternal infant care program in Minneapolis, Minnesota, during 1980-1982. White and black mothers were younger than the Hmong and other Asian mothers. The lowest mean age of 1st pregnancy was among blacks. Ages of 1st pregnancy were similar for whites, Hmong, and other Asians, although the mean age of menarche was approximately 2 years later for Hmong and other Southeast Asian mothers compared to the white and black mothers. Based on self reports at the 1st postpartum visit 1 month after delivery, 39% of the whites and 25% of the blacks were breastfeeding. In comparison 8.7% of the Hmong and 17% of the other southeast Asian mothers were breastfeeding. Maternal aged age at 1st pregnancy were significant predictors of parity for whites, blacks, Hmong, and other Southeast Asians. Ever-use of contraception was significant predictor of parity only for Hmong. The highest proportion of ever-users of contraception was among the white mothers (80%) followed by the blacks (69.3%) and other Asian mothers (34.85). Hmong mothers had the lowest proportion having used contraception (17.1%).     

Diabetes and the Gynecologist

The concept of a metabolic disorder of carbohydrate tolerance that progresses with age is examined. It is considered that acute exacerbations may occur at the time of puberty or during pregnancy or the menopause, leading to the development of manifest clinical diabetes.Pregnancy offers a unique opportunity for early diagnosis of potential diabetes in the mother. Existing screening tests are not satisfactory or reliable in uncovering this inborn error of metabolism that may lead to stillbirth or a grossly overweight baby, the onset of clinical diabetes in the mother occurring only many years later.Evidence is presented concerning four conditions that may cause maternal and fetal hyperinsulinism (the primary cause of fetal macrosomia). Also reported is the finding that approximately 50% of apparently normal women over the age of 50 show impaired glucose tolerance.     

Reproductive performance in a breeding colony of Brazilian squirrel monkeys (Saimiri sciureus).

In a captive colony of Brazilian squirrel monkeys (Saimiri sciureus) a discrete birth season has been retained for 5 years although its duration increased from 3 months in 1972 to 6 months in 1976. The ages of breeder females in this colony ranged from 3 to 14 years, and within this range reproductive performance was not affected by age, although it was significantly better in feral than in colony-born females. The latter had a lower pregnancy rate and a higher incidence of neonatal and fetal deaths than did the feral monkeys. It is our belief that the reproductive and maternal capabilities of the colony-born females were adversely affected by the practice of removing neonates from their mothers at weaning and raising them with age-mates.