The sex-ratio of singleton offspring in assisted-conception pregnancies

Abstract

To evaluate the effect of treatment and male factor infertility on the sex ratio of singleton births from assisted reproductive technology (ART). Retrospective analysis of singleton live births in the 2005 SART database, including fresh and frozen cycles, autologous and donor oocytes. The study population included 19,048 singleton pregnancies. The data were grouped into four cohorts defined by male factor infertility and either no use of ICSI or ICSI in some or all of the eggs. Factors studied included: maternal age, gravidity, diagnosis, oocyte and semen sources, semen collection method, assisted hatching, and number of oocytes or embryos transferred. Logistic regression was used to model the probability (odds ratio, OR, and 95% confidence interval, CI) of male infant overall, and within three maternal age groups (<35 years, 35–40 years, and >40 years). In the general population in the United States in 2004, 51.2% of live births were male. In the study population, the percentage of males was 49.9%, including 51.7% for births without ICSI and 48.9% with ICSI. The major factors influencing the sex ratio were use of ICSI, presence of male factor infertility and their interaction. The sex ratios for these factors are presented in the table below. Although all factors in the original model differed significantly between the four cohorts defined by ICSI and male factor infertility, none of them affected the sex ratio. The pattern of sex ratio across the four cohorts did not change after stratification by maternal age. TableNo ICSI No Male FactorNo ICSI Male FactorICSI No Male FactorICSI Male FactorN5,9915256,1396,393% Male (all)52.147.247.850.0OR (95% CI)1.00 (Reference)0.82 (0.69–0.98)0.84 (0.78–0.91)0.92 (0.86–0.98)% Male (Mothers <35 yrs)53.147.848.149.5OR (95% CI)1.00 (Reference)0.80 (0.61–1.05)0.82 (0.73–0.92)0.87 (0.78–0.96)% Male (Mothers 35–40 yrs)51.146.148.449.8OR (95% CI)1.00 (Reference)0.83 (0.61–1.14)0.90 (0.79–1.02)0.95 (0.84–1.08)% Male (Mothers >40 yrs)51.645.146.350.8OR (95% CI)1.00 (Reference)0.76 (0.50–1.16)0.82 (0.69–0.96)0.98 (0.81–1.19) Open table in a new tab Male factor infertility and the use of ICSI may reduce the chances of having a male child, although the mechanisms remain unclear.