The impact of consanguinity and inbreeding on perinatal mortality in Karachi, Pakistan

Close consanguineous unions continue to be extremely common in much of West Asia, including Pakistan. However, the impact of inbreeding on offspring mortality, particularly perinatal mortality, remains poorly documented. This paper attempts to measure the mortality risks associated with consanguinity and inbreeding while controlling for the effects of other potential confounders. The study sample comprises a multi-ethnic population residing in selected squatter settlements of Karachi. The adjusted odds ratio for perinatal mortality in the offspring of women married to their first cousins was 2.0 [95% CI 1.5, 2.6]. When parental inbreeding was also taken into account, the adjusted odds ratio for perinatal mortality increased further. Analysis of a subsample of data limited to pregnancies to women aged 35 years or above (at the time of the survey) showed that, despite adjustment for important biological and socio-demographic factors, both consanguinity and inbreeding remained important predictors of perinatal mortality in the offspring. Implications of the present study for further research are highlighted.

Associations between wife-beating and fetal and infant death: impressions from a survey in rural India

This report examines the linkages between wife-beating and one health-related consequence for women, their experience of fetal and infant mortality. Community-based data are used drawn from women surveyed in two culturally distinct sites of rural India: Uttar Pradesh in the north, in which gender relations are highly stratified, and Tamil Nadu in the south, in which they are more egalitarian. Results suggest that wife-beating is deeply entrenched, that attitudes uniformly justify wife-beating, and that few women can escape an abusive marriage. They also suggest that the health consequences of domestic violence--in terms of pregnancy loss and infant mortality--are considerable and that Indian women's experience of infant and fetal mortality is powerfully conditioned by the strength of the patriarchal social system. Results are tentative because of data limitations, but they are consistent and strong enough to warrant concern. They argue for the integration of services to identify, refer, and prevent domestic violence in the primary or reproductive health programs of the country and for the safe motherhood programs to be particularly vigilant, sensitive, and responsive to the conditions of battered women during pregnancy and the postpartum period.

The association between maternal HIV infection and perinatal outcome: a systematic review of the literature and meta-analysis

OBJECTIVE

To investigate the association between maternal HIV infection and perinatal outcome by a systematic review of the literature and meta-analysis.

METHODS

Appropriate publications were identified using electronic and hand searching of relevant journals from 1983 to 1996. Studies were included in the review if they were prospective cohorts with pregnant women identified as being HIV-infected with a control group of pregnant women who were not infected with HIV. Methodological quality was assessed for each study. Data were extracted for pre-determined outcome measures. Sensitivity analyses were performed to explore the association between HIV infection and an adverse perinatal outcome for the following study characteristics: clinical setting (developed or developing countries), methodological quality (high or poor) and whether studies controlled for potential confounding.

RESULTS

Thirty-one studies were eligible to be included in the review. The summary odds ratio of the risk of pre-defined adverse perinatal outcomes related to maternal HIV infection were as follows: spontaneous abortion 4.05 (95% CI 2.75-5.96); stillbirth 3.91 (95% CI 2.65-5.77); fetal abnormality 1.08 (95% CI 0.7-1.66); perinatal mortality 1.79 (95% CI 1.14-2.81); neonatal mortality 1.10 (95% CI 0.63-1.93); infant mortality 3.69 (95% CI 3.03-4.49); intrauterine growth retardation 1.7 (95% CI 1.43-2.02); low birthweight 2.09 (95% CI 1.86-2.35) and pre-term delivery 1 83 (95% CI 1.63-2.06). Sensitivity analyses showed that the association between infant mortality and maternal HIV infection was stronger in studies conducted in developing countries when compared with developed countries [odds ratios (OR) 3.72 (95% CI 3.05-4.54) and 8.6 (95% CI 0.53-141.05), respectively]; studies of higher methodological quality compared with those of poorer quality [odds ratios 14.57 (95% CI 6.93-30.65) and 3.37 (95% CI 2.74-4.14), respectively] and studies which had used restriction or matching to control for potential confounding factors compared with those that had not [OR 11.60 (95% CI 5.71-23.58) and 3.35 (95% CI 2.73-4.12), respectively].

CONCLUSIONS

The findings of this review have implications for women infected with HIV who are planning a pregnancy or who find themselves pregnant. There appears to be an association, although not strong, between maternal HIV infection and an adverse perinatal outcome. This relationship may be due to bias including uncontrolled or residual confounding. There does, however, appear to be a real and large increase in the risk of infant death in developing countries associated with maternal HIV infection, especially so when there has been an attempt to control for confounding.

Randomised trial of effects of vitamin supplements on pregnancy outcomes and T cell counts in HIV-1-infected women in Tanzania

BACKGROUND

In HIV-1-infected women, poor micronutrient status has been associated with faster progression of HIV-1 disease and adverse birth outcomes. We assessed the effects of vitamin A and multivitamins on birth outcomes in such women.

METHODS

In Tanzania, 1075 HIV-1-infected pregnant women at between 12 and 27 weeks' gestation received placebo (n=267), vitamin A (n=269), multivitamins excluding vitamin A (n=269), or multivitamins including vitamin A (n=270) in a randomised, double-blind, placebo-controlled trial with a 2x2 factorial design. We measured the effects of multivitamins and vitamin A on birth outcomes and counts of T lymphocyte subsets. We did analyses by intention to treat.

RESULTS

30 fetal deaths occurred among women assigned multivitamins compared with 49 among those not on multivitamins (relative risk 0.61 [95% CI 0.39-0.94] p=0.02). Multivitamin supplementation decreased the risk of low birthweight (<2500 g) by 44% (0.56 [0.38-0.82] p=0.003), severe preterm birth (<34 weeks of gestation) by 39% (0.61 [0.38-0.96] p=0.03), and small size for gestational age at birth by 43% (0.57 [0.39-0.82] p=0.002). Vitamin A supplementation had no significant effect on these variables. Multivitamins, but not vitamin A, resulted in a significant increase in CD4, CD8, and CD3 counts.

INTERPRETATION

Multivitamin supplementation is a low-cost way of substantially decreasing adverse pregnancy outcomes and increasing T-cell counts in HIV-1-infected women. The clinical relevance of our findings for vertical transmission and clinical progression of HIV-1 disease is yet to be ascertained.

The Collaborative Randomised Amnioinfusion for Meconium Project (CRAMP): 2. Zimbabwe

OBJECTIVE

To evaluate transcervical amnioinfusion for meconium stained amniotic fluid during labour.

DESIGN

Multicentre randomised controlled trial.

SETTING

A large urban academic hospital. Electronic fetal heart rate monitoring was not used.

PARTICIPANTS

Women in labour at term with moderate or thick meconium staining of the amniotic fluid.

INTERVENTIONS

Transcervical amnioinfusion of 500 mL saline over 30 minutes, then 500 mL at 30 drops per minute. The control group received routine care. Blinding of the intervention was not possible.

MAIN OUTCOME MEASURES

Caesarean section, meconium aspiration syndrome and perinatal mortality.

RESULTS

There was no difference in risk for caesarean section in the two groups (amnioinfusion 9.5% vs control 12.3%; RR 0.84, 95% CI 0.53-1.32). Meconium aspiration syndrome was significantly less frequent in the amnioinfusion group (3.1% vs 12.8%; RR 0.24, 95% CI 0.12-0.48), and there was a trend towards fewer perinatal deaths (1.2% vs 3.6%; RR 0.34, 95% CI 0.11-1.06).

CONCLUSIONS

Amnioinfusion is technically feasible in a developing country situation with limited intrapartum facilities. In this study amnioinfusion for meconium stained amniotic fluid was associated with striking improvements in perinatal outcome.

The Collaborative Randomised Amnioinfusion for Meconium Project (CRAMP): 1. South Africa

OBJECTIVE

To evaluate transcervical amnioinfusion for meconium stained amniotic fluid during labout.

DESIGN

Multicentre randomised controlled trial.

SETTING

Four urban academic hospitals in South Africa. Obstetric surveillance included the use of electronic fetal heart rate monitoring in most cases.

PARTICIPANTS

Women in labour at term with moderate or thick meconium staining of the amniotic fluid.

INTERVENTIONS

Transcervical amnioinfusion of 800 mL saline at 15 mL per minute, followed by a maintenance infusion at 3 mL per minute. The control group received routine care. Blinding of the intervention was not possible.

MAIN OUTCOME MEASURES

Caesarean section, meconium aspiration syndrome and perinatal mortality.

RESULTS

Caesarean section rates were similar (amnioinfusion group 70/167 vs control group 68/159; RR 0.98, 95% CI 0.76-1.26). The incidence of meconium aspiration syndrome was lower than expected on the basis of previous studies (4/162 vs 6/163; RR 0.67, 95% CI 0.19-2.33). There were no perinatal deaths. There were no significant differences between any of the subsidiary outcomes.

CONCLUSIONS

This study concurred with three previous trials which found no effect of amnioinfusion for meconium-stained amniotic fluid on caesarean section rate, though the pooled data from all identified trials to date show a significant reduction. The findings with respect to meconium aspiration syndrome were inconclusive in this study alone because of the small number of babies affected, but the point estimate of the relative risk was consistent with the finding of a significant reduction in previous studies and with the Zimbabwe arm (CRAMP 2) of this study. Pooled data clearly support the use of amnioinfusion for meconium stained amniotic fluid to reduce the incidence of meconium aspiration syndrome.

Why perinatal mortality cannot be a proxy for maternal mortality

In recent years, the perinatal mortality rate (PNMR) has been proposed as a proxy measure of maternal mortality, because perinatal deaths are more frequent and potentially more easily measured. This report assesses evidence for an association between these two statistics. This study, based upon data from Matlab, Bangladesh, shows that the maternal mortality ratio (MMR) and the PNMR do not vary together over time, and that the PNMR does not reliably indicate either the magnitude or the direction of change in the MMR from year to year. Statistical analysis shows that the correlation between the PNMR and the MMR is not significantly different from zero. An examination of the major causes of maternal and perinatal deaths indicates that the two measures cannot be expected to vary together. Almost half of perinatal deaths result from causes that do not pose a threat to the mother's life, and almost half of maternal deaths result from causes that do not lead to perinatal death. Monitoring of the PNMR can give an inaccurate picture of maternal mortality and should not be used as a proxy.

Delayed childbearing

Since around 1980, in countries belonging to European union the mean maternal age at birth increased by 1.5 y (from 27.1 to 28.6). This demographic change has important consequences on the health of the mother and of the neonate. Maternal mortality rates, stillbirth rates and frequency of congenital anomalies are affected. Without improvement in care those rates would have increased by 15 to 35% because of the increase of the mean age at birth. Nevertheless it should be noted that they continue to decrease.

Tick-borne relapsing fever and pregnancy outcome in rural Tanzania

OBJECTIVE

To assess the impact of tick-borne relapsing fever (TBRF) on the outcome of pregnancy.

DESIGN

Case control study of 137 pregnant women (cases) and 120 non-pregnant women (controls) with TBRF between 1985 and 1995.

SETTING

A rural hospital in Tabora Region, Tanzania.

RESULTS

Risk of birth during the attack of TBRF was 58.0%, with an extremely high perinatal mortality of 436 per 1000 births. The total loss of pregnancies including abortions was 475. per 1000. Case-fatality rate in pregnant women was 1.5%, compared to 1.7% in the non-pregnant women. A Jarisch-Herxheimer reaction was seen in 1.5% of the cases and in 1.7% of controls. Relapse rate was 3.6%, compared to 1.7% in non-pregnant women. Pregnant women with TBRF show higher densities of spirochetes than non-pregnant women (p < 0.001). The risk of delivery during the attack was positively correlated to increasing density of the spirochetemia (p < 0.001) and to gestational age (p < 0.001). Perinatal death was related to low birthweight (p < 0.001) and low gestational age (p < 0.001) and not to degree of spirochetemia.

CONCLUSIONS

The extremely high perinatal mortality rate during an attack asks for prevention and early effective management of TBRF. This is a challenge where access to health services in rural areas of developing countries is hampered by many factors.

Hypertensive disorders of pregnancy and maternal and foetal outcome: a case controlled study

A case controlled prospective study of 250 cases of hypertension complicating pregnancy (study group) and 400 normal pregnant women (control group) was carried out to determine the effect of hypertension on maternal and foetal outcome. Pregnancy induced hypertension was present in 96% cases and chronic hypertension in 4% cases. Preterm delivery (28.8% versus 3%), labour induction rate (52.8% versus 3.25%), caesarean section rate (14.8% versus 3.5%), stillbirth rate (4.8% versus 0.25%) and overall perinatal mortality rate (14.8% versus 1%) were higher in study group compared to controls. In study group (40%) babies required special nursery care compared to controls (6.75%). From these results it can be concluded that maternal hypertension is associated with adverse pregnancy outcome.

Impact of health centre availability on utilisation of maternity care and pregnancy outcome in a rural area of Haryana

Six hundred married women of 15-45 years age group were interviewed in 4 villages of the district Ambala in Haryana. Impact of health centre (HC) availability on the knowledge, opinion and practices related to maternity care and pregnancy outcome was assessed after adjusting the effect of socio-economic status. Except 17 women (2.8%), everyone knew at least one correct purpose of antenatal care (ANC) and 98.2% women had contacted health staff for ANC. However, knowledge of the respondents about the components of ANC was found to be poor in study villages. Traditional birth attendants (TBAs) conducted delivery in 76.1% cases in sub-centre (SC), 75.6% in villages without a HC compared to 49.8% in primary health centre (PHC) village. However, preference for TBAs in PHC village was 14.9%, in SC village 33.5%, and in villages without HC 36.3% (p < 0.001). Among respondents having better awareness about ANC components, preference and utilisation of modern delivery attendants was found to be higher. For maternity illnesses, consultation rate of government functionaries was 67.9% in PHC village, 52.2% in SC village and 55.8% in villages without a HC. Perinatal mortality rate of 76.0/1000 births in villages without HC was not significantly different from the rate of 87.4/1000 in SC village but rate of 38.9/1000 in the PHC village was significantly lower (p < 0.01). Awareness and availability of modern maternity services were found to have significant influence on the health seeking behaviour and pregnancy outcome.

Comparative study of intravaginal misoprostol with gemeprost as an abortifacient in second trimester missed abortion

This prospective, randomized study compared the efficacy of intravaginal misoprostol (Cytotec) and gemeprost (Cervagem) as an abortifacient for intrauterine deaths in second trimester pregnancy. Side-effects, complications and the cost-effectiveness associated with each drug were assessed. 21 out of 25 patients (84%) in the misoprostol group aborted whereas only 17 out of 25 patients (68%) in the gemeprost group aborted within 24 hours after the initiation of therapy. In the misoprostol group, the abortion rate was influenced by the gestational age with 100% abortion rate for those > 17 weeks' gestation compared to 67% for those with a gestational age of 13-16 weeks. Side-effects were rare in either group and no major complications were reported in either group. Misoprostol was definitely more cost-effective compared to gemeprost as the mean cost of inducing an abortion using misoprostol was RM 1.08 whereas that of gemeprost was RM 105. We thus concluded that misoprostol was at least as effective as gemeprost as an abortifacient for intrauterine death in second trimester pregnancy. Moreover, it was less costly, with very few side-effects.

Perinatal mortality rates and associated socio-demographic factors in two rural districts in Zimbabwe

OBJECTIVE

To determine perinatal mortality rates and associated socio-demographic factors in two rural districts in Zimbabwe.

DESIGN

Cross sectional community based survey.

SETTING

Murewa and Madziwa rural districts.

SUBJECTS

Women aged 15 to 50 years who had been pregnant over the preceding two years before the study.

MATERIALS AND METHODS

A questionnaire was administered to eligible women by trained interviewers. Information pertaining to the women's socio-demographic characteristics, reproductive health profile and pregnancy outcome was documented. A post hoc case control analysis was undertaken to determine the risk factors associated with poor perinatal outcome. Women who had a poor perinatal outcome were designated cases and those with a good outcome were designated controls.

RESULTS

The average perinatal mortality rate for both districts was 111 per 1,000 live births (Murewa 182 per 1,000 and Madziwa 48 per 1,000). Factors significantly associated with perinatal mortality were ethnicity, marital status, subjective standard of living and the women's level of formal education. Being Zezuru or being married was associated with poor perinatal outcome. Living well and having high levels of education were also associated with poor perinatal outcome. Perinatal mortality was not significantly associated with maternal age or spouse level of education.

CONCLUSION

This study showed unacceptability high perinatal mortality rates in these rural districts. The true socio-demographic factors associated with perinatal mortality could not be ascertained in this study because of confounding factors. There is need to study quality of antenatal, intrapartum and neonatal care offered by health centres in these districts. In addition there is need to strongly advocate a perinatal programme to address these high mortality rates.

Perinatal asphyxia: multivariate analysis of risk factors in hospital births

OBJECTIVE

To determine risk factors for perinatal asphyxia.

DESIGN

Cohort study.

SETTING

Teaching hospital.

METHODS

All consecutive hospital births were evaluated during the study period. Asphyxia was defined on intrapartum and neonatal resuscitation criteria. Maternal, intrapartum and neonatal variables were recorded in all births. Data was analyzed after stratifying for live and stillbirths by univariate and logistic regression analyses.

RESULTS

Amongst 2371 births (55 fetal deaths and 2316 live births), there were 86 cases of perinatal asphyxia (35 fetal deaths and 51 live births), providing an asphyxia rate of 36.3/1000 births. On multivariate analysis, risk factors significantly associated with asphyxia included prolonged second stage labor (OR 9.4), vaginal breech delivery (OR 6.6), elective cesarean delivery (OR 4.6), pregnancy induced hypertension (PIH) (OR 2.7) and fetal growth retardation (SFD) (OR 2.4). Amongst stillborn, the significant univariate factors associated with asphyxia were prolonged second stage labor (RR 1.7) and cord prolapse (RR 1.7).

CONCLUSIONS

There is a need to strengthen intrapartum management and early identification of mothers with PIH or intrauterine growth retardation to reduce asphyxial morbidity and mortality.

Constructing reproductive histories by linking vital records

Certificates of 1,449,287 live births and fetal deaths filed in Georgia from 1980 through 1992 were linked to create chronologies that, excluding induced abortions and ectopic pregnancies, constituted the reproductive experience of individual women. The authors initially used a deterministic method (whereby linking rules were not based on probability theory) to link as many records as possible, knowing that some of the linkages would be incorrect. They subsequently used a probabilistic method (whereby evaluation of linkages was developed from probability theory) to evaluate each linkage, and they broke those that were judged to be incorrect. Of the 1.4 million records, 38% did not link to another record. From the remaining records, 369,686 chains of two or more events were constructed. The longest chain included 12 events. Of the chains, 69% included two events; 22% included three events. Longer chains tended to have lower scores for probable validity. The probability-based evaluation of chains affected 3.0% of the records that had been in chains at the end of the deterministic linkage. A greater percentage of records in longer chains were affected by the evaluation. Unfortunately, the small subset of records that were the most difficult to link tended to overrepresent groups with the greatest risk of adverse pregnancy outcomes. Researchers contemplating a similar linkage can anticipate that, for the majority of records, linkage can be accomplished with a relatively straightforward, deterministic approach.

Acute intravaginal misoprostol toxicity with fetal demise

We report a case of an overdose with fetal demise from the intravaginal administration of misoprostol. A 25-yr-old gravid female self-administered 6000 micrograms misoprostol intravaginally and 600 micrograms orally. She rapidly developed shaking chills, abdominal and extremity cramping, emesis, and confusion. Hyperthermia and hypotension developed within 3.5 h after drug administration, with a temperature of 41.4 degrees C (106 degrees F). Ultrasound at 3.5 h after drug administration showed no fetal movement or heart motion. A nonviable fetus was delivered by emergent cesarean section. Treatment of the mother was supportive and included intravaginal decontamination and endotracheal intubation with neuroparalytic therapy to control agitation and hyperthermia. Recovery was complete within 15 h of drug administration.

Sex differentials in perinatal mortality in China and Finland

This study describes patterns of sex differentials in perinatal mortality in China and Finland. The analysis is based on three population-based one-year birth cohorts, one from Qingdao, China, in 1992 and two from Northern Finland in 1966 and 1985-86, comprised of 9,219, 11,422 and 9,207 singletons with at least 28 gestational weeks and 1000 g in birthweight, respectively. Both Finnish cohorts had an excess of male over female perinatal deaths, but in the Chinese cohort girls were more likely to die than boys. The adjusted odds ratio (OR) of perinatal mortality for boys was 1.31 (95 per cent confidence interval [CI] 0.98, 1.78) and 1.57 (95 per cent CI 0.89, 2.78) in the Finnish 1966 and 1985-86 cohorts, respectively, and 0.82 (95 per cent CI 0.55, 1.20) in the Chinese cohort. The corresponding figure for stillbirths in the Chinese was 0.57 (95 per cent CI 0.33, 0.98), which could explain the total excess of female deaths during the perinatal period. Our results suggest that the role of different social and cultural environments on the existing sex differentials in perinatal mortality between the countries needs further evaluation.

Reduction of maternal and perinatal mortality in rural and peri-urban settings: what works?

The purpose of this article is two-fold: (i) to lay out conceptual frameworks for programming in the fields of maternal and neonatal health for the reduction of maternal and peri/neonatal mortality; (ii) to describe selected MotherCare demonstration projects in the first 5 years between 1989 and 1993 in Bolivia, Guatemala, Indonesia and Nigeria. In Inquisivi, Bolivia, Save the Children/Bolivia, worked with 50 women's groups in remote rural villages in the Andean mountains. Through a participatory research process, the 'autodiagnosis', actions identified by women's groups included among others: provision of family planning through a local non-governmental organization (NGO), training of community birth attendants, income generating projects. In Quetzaltenango, Guatemala, access was improved through training of traditional birth attendants (TBAs) in timely recognition and referral of pregnancy/delivery/neonatal complications, while quality of care in health facilities was improved through modifying health professionals' attitude towards TBAs and clients, and implementation of management protocols. In Indonesia, the University of Padjadjaran addressed issues of referral and emergency obstetric care in the West-Java subdistrict of Tanjunsari. Birthing homes with radios were established in ten of the 27 villages in the district, where trained nurse/midwives provided maternity care on a regular basis. In Nigeria professional midwives were trained in interpersonal communication and lifesaving obstetric skills, while referral hospitals were refurbished and equipped. While reduction in maternal mortality after such a short implementation period is difficult to demonstrate, all projects showed improvements in referral and in reduction in perinatal mortality.

Fetal Candida infection associated with an intrauterine contraceptive device

Fetal Candida infection is rarely described but is often associated with a retained intrauterine contraceptive device (IUCD). A case of abortion due to Candida infection in a patient wearing an IUCD is reported.

Registration of births, stillbirths and infant deaths in Jamaica

BACKGROUND

Vital statistics underestimate the prevalence of perinatal and infant deaths. This is particularly significant when these parameters affect eligibility for international assistance for newly emerging nations.

OBJECTIVE

To determine the level of registration of livebirths, stillbirths and infant deaths in Jamaica.

METHODOLOGY

Births, stillbirths and neonatal deaths identified during a cross-sectional study (1986); and infant deaths identified in six parishes (1993) were matched to vital registration documents filed with the Registrar General.

RESULTS

While 94% of livebirths were registered by one year of age (1986), only 13% of stillbirths (1986) and 25% of infant deaths (1993) were registered. Post neonatal deaths were more likely to be registered than early neonatal deaths. Frequently the birth was not registered when the infant died. Birth registration rates were highest in parishes with high rates of hospital deliveries (rs = 0.97, P < 0.001) where institutions notify the registrar of each birth. Hospital deaths, however, were less likely to be registered than community deaths as registrars are not automatically notified of these deaths.

CONCLUSIONS

To improve vital registration, institutions should become registration centres for all vital events occurring there (births, stillbirths, deaths). Recommendations aimed at modernizing the vital registration system in Jamaica and other developing countries are also made.

Prolonged induction to delivery time in termination of pregnancy using 16, 16-dimethyl-PGE1-methyl ester (gemeprost) for fetuses with a neural tube defect or hydrocephalus

A retrospective study is reported comparing the induction to delivery interval using gemeprost for termination of pregnancy, in the second trimester, in 3 groups of patients. It was observed that the mean induction to delivery interval was significantly longer in 75 pregnancies where there was a fetus with a neural tube defect and or hydrocephalus (31.7 hours) compared with 88 pregnancies with other fetal abnormalities (19.7 hours) and 84 pregnancies where there was an intrauterine death (11.3 hours). There was also an increase in the requirements for further intervention to obtain delivery in the group with a neural tube defect or hydrocephalus (n = 33) compared with where there was an intrauterine fetal death (n = 4) and other abnormality (n = 14). We believe these results should be considered when counselling patients who have requested termination of pregnancy for fetal abnormalities.

Early selection and sex composition in Italy: a study at the regional level

We have chosen four Italian regions with different degrees of industrialization and socioeconomic levels to study environmental differences in the sex ratio. The improvement in living and sanitary conditions during the last century has led to a progressive reduction in early male extramortality, and the sex ratio at birth has been almost unchanged at least to the first year of life and probably up to reproductive age. To investigate whether socioeconomic, cultural, or biological factors still influence the sex ratio at birth, we studied the stillbirth rate and the relations between newborn viability and sex composition as a function of maternal age and educational level. Our results suggest that in less favorable environments early selection against male newborns is almost twice that against female newborns when the mothers are the least favored for socioeconomic status, cultural level, and biological conditions (older than 39 years).