Sex ratios at birth in Australia according to mother's country of birth: A national study of all 5 614 847 reported live births 1997-2016.

OBJECTIVES: Son preference and sex selective practices have resulted in a deficit of girls in several countries, primarily across Asia. Emerging evidence indicates that son preference survives migration to Western high-income countries. The objective of this study was to assess male-to-female (M/F) ratios at birth per mother's country of birth in Australia 1997-2016, in total and by parity, and by states/territories and over time. METHODS: Data for this national population-based cross-sectional study were obtained from the National Perinatal Data Collection (NPDC) and included all live births in Australia 1997-2016 (N = 5 614 847). M/F ratios with 95% Confidence Intervals were estimated. RESULTS: The M/F ratio for births to Australian-born mothers was within the expected range (1.03-1.07) regardless of parity and time period. M/F ratios were elevated above the expected range for births to mothers born in China in the total sample (M/F ratio 1.084, 95% confidence interval 1.071-1.097) and at parity 2 (1.175, 1.120-1.231), and for births to mothers born in India at parity 2 (1.146, 1.090-1.204). Parity 2 births were the most consistently male-biased across time. Across states, elevated M/F ratios were identified for both groups in New South Wales (China parity 2: 1.182, 1.108-1.260; India parity 2: 1.182, 1.088-1.285), for births to Chinese-born mothers in Victoria (total births: 1.097, 1.072-1.123; parity 1: 1.115, 1.072-1.159) and Australian Capital Territory (total births: 1.189, 1.085-1.302) and births to Indian-born mothers Western Australia (parity 2: 1.307, 1.122-1.523). CONCLUSIONS: Son preference persists in some immigrant communities after migration to Australia. The consistent pattern of elevated M/F ratios across the larger states indicates that sex imbalances at birth are largely independent of restrictiveness of local abortion laws. Drivers and consequences of son preference in Western high-income settings should be explored to further promote gender equality, and to strengthen support for women who may be vulnerable to reproductive coercion.

Trends in missing females at birth in India from 1981 to 2016: analyses of 2·1 million birth histories in nationally representative surveys.

BACKGROUND: Half of the world's missing female births occur in India, due to sex-selective abortion. It is unknown whether selective abortion of female fetuses has changed in recent years across different birth orders. We sought to document the trends in missing female births, particularly among second and third children, at national and state levels. METHODS: We examined birth histories from five nationally representative household surveys (National Family Health Surveys 1-4 and District Level Household Survey 2) to compute the conditional sex ratio (defined as the number of girls born per 1000 boys depending on previous birth sex) in India during 1981-2016. We estimated decadal variation in conditional sex ratio for 1987-96, 1997-2006, and 2007-16, and quantified trends in the numbers of missing female births for the states constituting >95% of India's population, as well as in 5-year intervals for each survey round. We used multivariate logistic regression to calculate the odds ratio of a second (or third) girl depending on the sex of the earlier child (or children), adjusting for education, wealth, religion, caste, and place of residence. FINDINGS: We assessed 2·1 million birth histories across the five surveys. Applying the conditional sex ratios from the surveys to national births, we found that 13·5 million female births were missing during the three decades of observation (1987-2016), on the basis of a natural sex ratio of 950 girls per 1000 boys. Missing female births increased from 3·5 million in 1987-96 to 5·5 million in 2007-16. Contrasting the conditional sex ratio from the first decade of observation (1987-96) to the last (2007-16) showed worsening for the whole of India and almost all states, among both birth orders. Punjab, Haryana, Gujarat, and Rajasthan had the most skewed sex ratios, comprising nearly a third of the national totals of missing second-born and third-born females at birth. From about 1986, the conditional sex ratio for second-order or third-order births after an earlier daughter or daughters diverged notably from that after an earlier son or sons. From 1981 to 2016, the sex ratio for second-born children after an earlier daughter decreased from 930 (99% CI 869-990) to 885 (859-912), and that for third-born children after two earlier daughters decreased from 968 (866-1069) to 788 (746-830). The probability of missing girls was mostly determined by earlier daughters, even after considering wealth quintile and education levels. The conditional sex ratio among the richest and most educated mothers was most distorted compared with lower wealth and education groups, and generally decreased with time, until a modest improvement in 2007-16. INTERPRETATION: In contrast to the substantial improvements in female child mortality in India, missing female births, driven by selective abortion of female fetuses, continues to increase across the states. Inclusion of a question on sex composition of births in the forthcoming census would provide local information on sex-selective abortion in each village and urban area of the country. FUNDING: None. TRANSLATION: For the Hindi translation of the abstract see Supplementary Materials section.

On the estimation of female births missing due to prenatal sex selection.

This research note is prompted by a paper by Kashyap (Is prenatal sex selection associated with lower female child mortality? Population Studies 73(1): 57-78). Kashyap's paper, which provides 40 original estimates of missing female births, relies on an alternative definition of missing female births, leading to estimates of about half the magnitude of other estimates. There appears, therefore, a real need to take stock of the concept of missing female births widely used by statisticians around the world for assessing the demographic consequences of prenatal sex selection. This research note starts with a brief review of the history of the concept and the difference between Amartya Sen's original method and the alternative method found elsewhere to compute missing female births. We then put forward three different arguments (deterministic and probabilistic approaches, and consistency analysis) in support of the original computation procedure based on the number of observed male births and the expected sex ratio at birth.

Sex selection and non-invasive prenatal testing: A review of current practices, evidence, and ethical issues.

Non-invasive prenatal testing (NIPT) can determine the sex of the fetus very accurately and very early in gestation. There are concerns that the ease, timing, and accuracy of NIPT sex determination will facilitate sex-selective termination of pregnancy (TOP). Here, we review current practices, the evidence for a link between NIPT and sex-selective TOP, and associated ethical issues. Sex-selective TOP, usually motivated by son preference, has had serious demographic consequences in countries such as India and China. Currently, ultrasound is the primary method by which parents determine the sex of the fetus. The diffusion of ultrasound technology has had a direct impact on the rates of sex-selective TOP. Although NIPT is currently more costly, it is feasible that increased uptake of this technology could have a similar effect. Partly because NIPT is a relatively recent development in prenatal screening, there is little data on the impact of NIPT on sex selection practices. Evidence that NIPT is playing a role in sex-selective TOP remains largely anecdotal. Further research is required to assess and quantify TOP resulting from NIPT sex determination. The use of these technologies for sex selection raises a number of ethical issues, in addition to practical demographic consequences.

Trends and correlates of the sex distribution among U.S. assisted reproductive technology births.

OBJECTIVE: To assess national trends in the sex distribution of live-born infants in the assisted reproductive technology (ART) and general population and to identify factors correlated with offspring sex. DESIGN: Retrospective cohort study. SETTING: Fertility treatment centers. PATIENTS: All live-born infants included in the National Vital Statistics System and resulting from ART cycles reported to the National ART Surveillance System during 2006-14. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE(S): Trends in the proportion of male infants in the general population and proportion of males from fresh ART cycles among all ART live-born infants and singletons after single ET. RESULT(S): There were 214,274 live-born infants resulting from fresh ART cycles; 53.5% (5,492/10,266) of infants resulting from PGD/PGS cycles were male, as compared with 50.6% (103,228/204,008) in the non-PGD/PGS group. Among non-PGD/PGS cycles, blastocyst transfer was positively associated with male infants (adjusted risk ratio [aRR] = 1.03; 95% confidence interval [CI], 1.02-1.04). Intracytoplasmic sperm injection was negatively associated with male infants (aRR = 0.94; 95% CI, 0.93-0.95) and for singletons after single ET (aRR = 0.93; 95% CI, 0.90-0.95), as was transfer of two embryos (aRR 0.98; 95% CI, 0.97-0.99) or three or more embryos (aRR = 0.98; 95% CI, 0.96-0.99) among all live births from cycles without PGD/PGS use. CONCLUSION(S): The proportion of male live-born infants among ART population did not change during 2006-14, ranging from 50.5% to 51.2%. Factors such as blastocyst transfer, intracytoplasmic sperm injection use, embryo stage, and number of embryos transferred may be associated with infant sex; further investigation is needed to understand possible underlying causes.

Is prenatal sex selection associated with lower female child mortality?

I examine whether prenatal sex selection has substituted postnatal excess female mortality by analysing the dynamics of child sex ratios between 1980 and 2015 using country-level life table data. I decompose changes in child sex ratios into a 'fertility' component attributable to prenatal sex selection and a 'mortality' component attributable to sex differentials in postnatal survival. Although reductions in numbers of excess female deaths have accompanied increases in missing female births in all countries experiencing the emergence of prenatal sex selection, relative excess female mortality has persisted in some countries but not others. In South Korea, Armenia, and Azerbaijan, mortality reductions favouring girls accompanied increases in prenatal sex selection. In India, excess female mortality was much higher and largely stable as prenatal sex selection emerged, but slight reductions were seen in the 2000s. In China, although absolute measures showed reductions, relative excess female mortality persisted as prenatal sex selection increased.

Sex selection in late Iberian infant burials: Integrating evidence from morphological and genetic data.

OBJECTIVE: The aim of this study was to analyze the infant burials found inside Iberian homes in relation to a possible case of sex selection. METHODS: The study included the remains of 11 infant individuals buried under the 10 houses excavated in the late Iberian village of Camp de les Lloses (Tona, Barcelona, Spain). Sex was determined using genetic analysis. RESULTS: Our results showed that almost all the burials were females. However, the age interval of death was wide enough to weaken the premise of infanticide, and the burials probably represent cases of natural death. DISCUSSION: Infanticide in its different forms has long been argued as an explanation for the infant remains found throughout various burial sites. Many authors thought that infanticide, mainly femicide, was the main method of population control in ancient times. However, there is no anthropological evidence (age distribution and sex analyzed genetically) to support the intentional killing of females in this or in other cases. We hypothesized that there was a positive selection for females to be buried inside the houses, probably related to their benefactor roles.

Male-biased sex ratios in Australian migrant populations: a population-based study of 1 191 250 births 1999-2015.

Background: The naturally occurring male-to-female (M/F) ratio at birth is 1.05. Higher ratios found primarily in countries across Asia have been attributed to prenatal sex selection due to son preference. There is growing evidence that sex-selective practices continue following migration; however, little is known about these practices following migration to Australia. Methods: In this population-based study we assessed M/F ratios at birth per mother's country of birth for all registered births 1999-2015 in Victoria, Australia (n = 1 191 250). We also compared the M/F ratio among births to mothers born elsewhere to that of mothers born in Australia, stratified by time period and parity. Results: Compared with the naturally occurring M/F ratio as well as to the M/F ratio among births to mothers born in Australia, there was an increased ratio of male births to mothers born in India, China and South-East Asia, particularly at higher parities and in more recent time periods (elevated M/F ratios ranged from 1·079 to 1·248, relative risks of male birth ranged from 1·012 to 1·084 with confidence intervals between 1·001 and 1·160 and P-values between 0·005 and 0·039). The most male-biased sex ratios were found among multiple births to Indian-born mothers, and parity of two or more births to Indian and Chinese-born mothers in 2011-15. Conclusions: The male-biased sex ratios observed in this study indicate that prenatal sex selection may be continuing following migration to Australia from countries where these practices have been documented. The excess of males among multiple births raises the question as to what role assisted reproduction plays. Findings also suggest that systematic discrimination against females starts in the womb.

Violence, selection and infant mortality in Congo.

This paper documents the effects of the recent civil war in the Democratic Republic of Congo on mortality both in utero and during the first year of life. It instruments for conflict intensity using a mineral price index, which exploits the exogenous variation in the potential value of mineral resources generated by changes in world mineral prices to predict the geographic distribution of the conflict. Using estimates of civil war exposure on mortality across male and female newborn to assess their relative health, it provides evidence of culling effect (in utero selection) as a consequence of in utero shocks.

Sex selection and health at birth among Indian immigrants.

I use birth-certificate data for Spain to document extremely son-biased sex ratios at birth among Indian immigrants (122 boys per 100 girls), especially at higher parities. I also show that the children of Indian immigrants display poor health outcomes during infancy. For instance, almost 10% of boys with Indian parents are born prematurely, compared with 6% of boys with native parents. However, there is no evidence of a gender gap in infant health among the children of Indian immigrants. I provide evidence suggesting that the poor outcomes of Indian children at birth may be attributed to the low endowments of Indian mothers, while the absence of a gender gap may be driven by the fact that the parents who would invest less in girls are less likely to carry the pregnancies of girls to term (more likely to practice sex-selective abortion), combined with the lower cost of prenatal investments in Spain (compared with India).

Sex selection for non-medical indications: a survey of current pre-implantation genetic screening practices among U.S. ART clinics.

PURPOSE: This study aimed to determine the current percentage of United States (U.S.) assisted reproductive technology (ART) clinics offering sex selection via pre-implantation genetic screening (PGS) for non-medical purposes. METHODS: The authors conducted website review and telephone interview survey of 493 U.S. ART clinics performing in vitro fertilization (IVF) in 2017. Main outcome measures were pre-implantation genetic screening (PGS)/pre-implantation genetic diagnosis (PGD) practices and non-medical sex selection practices including family balancing. RESULTS: Of the 493 ART clinics in the USA, 482 clinics (97.8%) responded to our telephone interview survey. Among all U.S. ART clinics, 91.9% (n = 449) reported offering PGS and/or PGD. Furthermore, 476 clinics responded to survey questions about sex selection practices. Of those ART clinics, 72.7% (n = 346) reported offering sex selection. More specifically among those clinics offering sex selection, 93.6% (n = 324) reported performing sex selection for family balancing, and 81.2% (n = 281) reported performing for elective purposes (patient preference, regardless of rationale for the request). For couples without infertility, 83.5% (n = 289) of clinics offer sex selection for family balancing and 74.6% (n = 258) for non-specific elective reasons. CONCLUSIONS: The majority of U.S. ART clinics offer non-medical sex selection, a percentage that has increased substantially since last reported in 2006.

Use of Sex Selection Techniques for Social Reasons: A Menace.

Sex selection skewed towards males is a malady that our society is grappling with. The desire to have a child of preferred gender has encouraged people to move beyond the ambit of traditions and explore scientific methods. Despite the controversies around sex-selection for social reasons and strong regulatory mechanisms in place, the demand for such measures has not gone down. On the contrary, traditional practice of consuming indigenous medicines during pregnancy for a male child continues. Recent research highlights the harms of this practice in the form of birth defects and stillbirths. This has led to stricter enforcement of PCPNDT Act and has stimulated the propagation of messages on the harms of these practices in the community.

The Dynamics of Son Preference, Technology Diffusion, and Fertility Decline Underlying Distorted Sex Ratios at Birth: A Simulation Approach.

We present a micro-founded simulation model that formalizes the "ready, willing, and able" framework, originally used to explain historical fertility decline, to the practice of prenatal sex selection. The model generates sex ratio at birth (SRB) distortions from the bottom up and attempts to quantify plausible levels, trends, and interactions of son preference, technology diffusion, and fertility decline that underpin SRB trajectories at the macro level. Calibrating our model for South Korea, we show how even as the proportion with a preference for sons was declining, SRB distortions emerged due to rapid diffusion of prenatal sex determination technology combined with small but growing propensities to abort at low birth parities. Simulations reveal that relatively low levels of son preference (about 20 % to 30 % wanting one son) can result in skewed SRB levels if technology diffuses early and steadily, and if fertility falls rapidly to encourage sex-selective abortion at low parities. Model sensitivity analysis highlights how the shape of sex ratio trajectories is particularly sensitive to the timing and speed of prenatal sex-determination technology diffusion. The maximum SRB levels reached in a population are influenced by how the readiness to abort rises as a function of the fertility decline.

Risk Factors for Stillbirth: Findings from a Population-Based Case-Control Study, Haryana, India.

BACKGROUND: Stillbirth is a prevalent adverse outcome of pregnancy in India despite efforts to improve care of women during pregnancy. Risk factors for stillbirths include sociodemographic factors, medical complications during pregnancy, intake of harmful drugs, and complications during delivery. The objective of the study was to examine the risk factors for stillbirth with a focus on sex selection drugs (SSDs). METHODS: A population-based case-control study was undertaken in Haryana. Cases of stillbirths were identified from the Maternal Infant Death Review System portal of Haryana state for the months of August-September 2014. A consecutive birth from the same geographical area as the case was selected as the control. The sample size was 325 per group. Mothers were interviewed using a validated tool. Bivariate analyses and logistic regression were conducted to examine the association between risk factors and stillbirth. Attributable risk proportions (ARP) and population attributable risk proportions (PARP) were estimated. RESULTS: The sociodemographic profiles of the cases and controls were similar. History of intake of SSDs [adjusted odds ratio (OR) 2.6, 95% confidence interval (CI) 1.5, 4.5] emerged as a risk factor. Other significant factors were preterm <37 weeks (OR 3.5, 95% CI 2.1, 6.0), history of previous stillbirths (OR 4.0, 95% CI 2.1, 7.8), and complications during labour (OR 3.3, 95% CI 2.1, 5.3). Estimates of the ARP and PARP for intake of SSDs were 0.60 (95% CI 0.32, 0.77) and 0.1 (95% CI -0.13, 0.28), respectively. CONCLUSIONS: SSDs could be attributed as a risk factor in a fifth of the cases of stillbirths. The number needed to harm for the use of SSDs in causing adverse effect of stillbirths was 5, suggesting thereby that for every five mothers exposed to SSDs, one would have stillbirth. Greater efforts are required to inform people about the harmful effects of SSD consumption during pregnancy.

Stillbirth and the small fetus: use of a sex-specific versus a non-sex-specific growth standard.

OBJECTIVE: To determine if the use of a sex-specific standard to define small-for-gestational age (SGA) will improve prediction of stillbirth. STUDY DESIGN: We performed a retrospective cohort study of singleton pregnancies excluding anomalies, aneuploidy, undocumented fetal sex or birthweight. SGA was defined as birthweight <10th percentile by the non-sex-specific and sex-specific Alexander standards. The association between SGA and stillbirth using these standards was assessed using logistic regression. RESULT: Among 57,170 pregnancies meeting inclusion criteria, 319 (0.6%) pregnancies were complicated by stillbirth. The area under the receiver operating characteristic curve for the prediction of stillbirth was greater for the sex-specific compared to the non-sex-specific standard (0.83 vs 0.72, P<0.001). CONCLUSION: Our findings suggest adoption of a sex-specific standard for diagnosis of SGA as it is more discriminative in identifying the SGA fetus at risk for stillbirth.

Sex ratio at birth in twenty-first century Greece: the role of ethnic and social groups.

The number of male per 100 female live births (defined as the sex ratio at birth, SRB) has been shown to be consistently stable in human populations irrespective of time and geographical location. All over the globe approximately 105 boys are born for every 100 girls and any significant deviation from this 'global average' is considered to be unnatural and is attributed to sex-selective under-reporting of births, sex-selective abortion, sex-selective infanticide or other man-made factors. The present paper uses data on civil registration from 2004-2011 to investigate the sex ratio at birth in modern Greece. It was found that the SRB is extremely masculine when the parents originate from the Indian sub-continent and China. The SRB is also unnaturally high (more than 113 boys per 100 girls) in the case of legitimate births born to Greek mothers who are illiterate. These findings are strong evidence that sex-selective abortions are taking place in Greece within population groups with a certain ethnic and social profile. Other parameters, such as age of mother at birth, birth order, legal status of birth and geographical location, were also investigated and they were found to play a role in the variation of SRB, but not to the extent education and ethnic group do.

Winning the genetic lottery: biasing birth sex ratio results in more grandchildren.

Population dynamics predicts that on average parents should invest equally in male and female offspring; similarly, the physiology of mammalian sex determination is supposedly stochastic, producing equal numbers of sons and daughters. However, a high quality parent can maximize fitness by biasing their birth sex ratio (SR) to the sex with the greatest potential to disproportionately outperform peers. All SR manipulation theories share a fundamental prediction: grandparents who bias birth SR should produce more grandoffspring via the favored sex. The celebrated examples of biased birth SRs in nature consistent with SR manipulation theories provide compelling circumstantial evidence. However, this prediction has never been directly tested in mammals, primarily because the complete three-generation pedigrees needed to test whether individual favored offspring produce more grandoffspring for the biasing grandparent are essentially impossible to obtain in nature. Three-generation pedigrees were constructed using 90 years of captive breeding records from 198 mammalian species. Male and female grandparents consistently biased their birth SR toward the sex that maximized second-generation success. The most strongly male-biased granddams and grandsires produced respectively 29% and 25% more grandoffspring than non-skewing conspecifics. The sons of the most male-biasing granddams were 2.7 times as fecund as those of granddams with a 50∶50 bias (similar results are seen in grandsires). Daughters of the strongest female-biasing granddams were 1.2 times as fecund as those of non-biasing females (this effect is not seen in grandsires). To our knowledge, these results are the first formal test of the hypothesis that birth SR manipulation is adaptive in mammals in terms of grandchildren produced, showing that SR manipulation can explain biased birth SR in general across mammalian species. These findings also have practical implications: parental control of birth SR has the potential to accelerate genetic loss and risk of extinction within captive populations of endangered species.