Prenatal sex selection and female infant mortality are more common in India after firstborn and second-born daughters

Girls start life on an uneven playing field

Background and objectives

Evolutionary research on the sex ratio at birth (SRB) has focused on explaining variability within and between populations, and whether parental fitness is maximized by producing daughters or sons. We tested predictors of SRB in a low-income setting, to understand whether girls differ from boys in their likelihood of being born into families with the capacity to invest in them, which has implications for their future health and fitness.

Methodology

We used data from a cluster randomized control trial from lowland rural Nepal (16 115 mother-child dyads). We applied principal component analysis to extract two composite indices reflecting maternal socio-economic and reproductive (parity, age) capital. We fitted mixed-effects logistic regression models to estimate odds ratios of having a girl in association with these individual factors and indices.

Results

The SRB was 112. Compared to the global reference SRB (105), there were seven missing girls per 100 boys. Uneducated, early-marrying, poorer and shorter mothers were more likely to give birth to girls. Analysing composite maternal indices, lower socio-economic and reproductive capital were independently associated with a greater likelihood of having a girl.

Conclusions and implications

In this population, girls start life facing composite disadvantages, being more likely than boys to be born to mothers with lower socio-economic status and reproductive capital. Both physiological and behavioural mechanisms may contribute to these epidemiological associations. Differential early exposure by sex to maternal factors may underpin intergenerational cycles of gender inequality, mediated by developmental trajectory, education and socio-economic status.

Intention to have a second child, family support and actual fertility behavior in current China: An evolutionary perspective

OBJECTIVES

This study provides an evolutionary perspective to a classic topic in demography, that is, the discrepancy between reproductive intention and subsequent behavior, in the context of China's two-child policy.

METHODS

We conduct an event history analysis of longitudinal data from the 2015 and 2018 waves of the Xi'an Fertility Survey (sample size = 321 followed one-child mothers) to test the hypotheses of how within-family support/conflict affects women's fertility behavior.

RESULTS

Only 50% of positive intentions (i.e., intending to have a second child) led to another (live) birth within the 3-year interval; meanwhile, 15% of uncertain intentions and 5% of negative intentions resulted in a birth. Husband's and the firstborn's emotional support raised the hazard of second childbirth along maternal life course, which cannot be fully mediated by mother's fertility intention and thus, contributed to an intention-behavior gap. Husband's sibship size had dual effects on female childbearing behavior: A positive indirect effect mediated by fertility intention, but a negative direct effect presumably due to sibling competition for intergenerational support. Finally, after controlling for fertility intention, having a firstborn son was still associated significantly with a lower second-childbirth hazard, presumably due to son preference as well as concern over parental investment.

CONCLUSIONS

Our study identifies a discrepancy between maternal fertility intention and realized childbearing, which was partly explained by (lack of) support from other (multiple) stakeholders in family reproduction.

Prevalence and correlates of sex-selective abortions and missing girls in Nepal: evidence from the 2011 Population Census and 2016 Demographic and Health Survey

OBJECTIVES

These were to: (1) produce national and subnational estimates of the sex ratio at birth (SRB) and number of missing girl births in Nepal and (2) understand the socioeconomic correlates of these phenomena.

DESIGN

Observational secondary data analysis of (1) the 2011 population census of Nepal and (2) the Nepal Demographic and Health Survey (DHS) 2006, 2011 and 2016.

SETTING

Nepal.

PARTICIPANTS

(1) 2 567 963 children age 0-4 in the 2011 population census and (2) 27 329 births recorded in DHSs.

PRIMARY AND SECONDARY OUTCOMES

We estimate the SRB, and number and proportion of missing girls in the year and 5 years before the census by district. We also calculate conditional sex ratios (the SRB dependant on parity and sex of previous children) by province, time, education and wealth.

RESULTS

We find that 11 districts have significantly skewed sex ratios at birth in the 2011 population census, with the highest SRBs observed in Arghakhanchi (SRB=127) and Bhaktapur (SRB=123). 22 540 girl births were missing in the 5 years before the 2011 population census. Sex-selective abortion is geographically concentrated, especially in the Kathmandu Valley and Lumbini Province, with 53% of missing girls found in only 11 out of 75 districts.DHS data confirm this, with elevated conditional sex ratios observed in Bagmati and Lumbini Provinces; conditional sex ratios where previous births were all female also became more skewed over time. Skewed sex ratios are concentrated among wealthier more educated groups.

CONCLUSIONS

It is clear that sex selection will persist and develop in Nepal unless a coordinated effort is made to address both the demand for and supply of this service. Policies should be holistic and encompass economic and legal gender equity, and strengthen monitoring mechanisms to prevent technology misuse, without jeopardising the right to safe, free and legal abortion.

A scoping review of methods for assessment of sex differentials in early childhood mortality

BACKGROUND

While assessment of sex differentials in child mortality is straightforward, their interpretation must consider that, in the absence of gender bias, boys are more likely to die than girls. The expected differences are also influenced by levels and causes of death. However, there is no standard approach for determining expected sex differences.

METHODS

We performed a scoping review of studies on sex differentials in under-five mortality, using PubMed, Web of Science, and Scopus databases. Publication characteristics were described, and studies were grouped according to their methodology.

RESULTS

From the 17,693 references initially retrieved we included 154 studies published since 1929. Indian, Bangladeshi, and Chinese populations were the focus of 44% of the works, and most studies addressed infant mortality. Fourteen publications were classified as reference studies, as these aimed to estimate expected sex differentials based upon the demographic experience of selected populations, either considered as gender-neutral or not. These studies used a variety of methods - from simple averages to sophisticated modeling - to define values against which observed estimates could be compared. The 21 comparative studies mostly used life tables from European populations as standard for expected values, but also relied on groups without assuming those values as expected, otherwise, just as comparison parameters. The remaining 119 studies were categorized as narrative and did not use reference values, being limited to reporting observed sex-specific estimates or used a variety of statistical models, and in general, did not account for mortality levels.

CONCLUSION

Studies aimed at identifying sex differentials in child mortality should consider overall mortality levels, and report on more than one age group. The comparison of results with one or more reference values, and the use of statistical testing, are strongly recommended. Time trends analyses will help understand changes in population characteristics and interpret findings from a historical perspective.

Associations Between Sex Composition of Older Siblings and Infant Mortality in India from 1992 to 2016

BACKGROUND

This study examines associations between sex composition of older siblings and infant mortality by sex, to guide efforts to address excess female infant mortality in India.

METHODS

We conducted a retrospective cross-sectional study of infant mortality in India using four waves of data from the nationally-representative National Family Health Survey, collected between 1992 and 2016 (unweighted N = 338,504 for children aged 1-5). We used sex-stratified multivariable logistic regression models to assess the associations between sex composition of older siblings and risk of infant mortality.

FINDINGS

Male infants with two living older sisters and no living older brothers had lower odds of infant mortality relative to those with one living older brother (e.g., 2015-16 AOR 0.62, 95% CI 0.50-0.76); this effect was significant for boys across all waves of data but was not seen for girls in any wave. Exploratory models focused on third order births found that boys were less likely than girls to die in infancy if born subsequent to two older sisters (2015-16 AOR 0.48, 95% CI 0.31-0.74); analysis of crude prevalence data indicated that this converts into a 64% greater risk for infant mortality for girls relative to boys in this third-order group.

INTERPRETATION

Higher birth order males with older sisters have greater protection against infant mortality, a finding that has persisted for over 25 years. To address ongoing gender inequities in infant survival in India, greater focus is needed to support higher birth order girls and social norm movements against son preference.

Why so many Agta boys? Explaining 'extreme' sex ratios in Philippine foragers

Male-biased sex ratios have been observed in multiple small-scale societies. Although intentional and systematic female-biased mortality has been posited as an explanation, there is often a lack of ethnographic evidence of systematic female neglect and/or infanticide. The Agta, a foraging population from the Philippines, have a skewed sex ratio of 1.29 (129 males per 100 females) aged 15 years or under. We hypothesised that this skew was not caused by greater female deaths, but due to an adaptive response, where more males were produced at birth in reaction to high male-biased extrinsic mortality. To test this hypothesis we utilise census, childcare and mortality data from 915 Agta. The Agta's sex ratio is significantly male-biased in the <1 (n = 48, 2:1) and 1-5 year (n = 170, 1.39:1) age cohorts; however, we find no evidence of systematic female neglect in patterns of childcare. Furthermore, the sex ratio decreases over cohorts, becoming balanced by the end of the juvenile period, owing to significantly higher male mortality. Taken together, these results are not supportive of female infanticide or neglect, and instead suggest an adaptive mechanism, acting in utero as a response to male-biased juvenile mortality, following Fisherian principles of equalising parental investment.