Late termination of pregnancy at a major Queensland tertiary hospital, 2010-2020.

OBJECTIVE: To review rates of and indications for late pregnancy feticide at a major Queensland tertiary perinatal centre over the past decade. DESIGN: Retrospective cohort study. SETTING, PARTICIPANTS: The Centre for Advanced Prenatal Care at the Royal Brisbane and Women's Hospital, a tertiary perinatal centre; feticides of singleton pregnancies of at least 22 weeks' gestation, 1 January 2010 - 31 December 2020. MAIN OUTCOME MEASURES: Indications for feticide; median gestational age at feticide; referral source; time between referral, maternal-fetal medicine review, and feticide. RESULTS: During 2010-2020, 305 feticides were undertaken at 22 weeks' gestation or later. The annual number of feticides increased from 20 in 2010 to 54 in 2020. The median gestational age at feticide was consistent across the decade (24+6 weeks; range, 17+0 to 37+1 weeks). The most frequent fetal indications for feticide were neurological abnormalities (110 of 305, 36%), aneuploidy or genetic syndromes (67, 22%), and cardiac malformations (59, 19%). Most women were seen for review within seven days of referral for feticide (154 of 197 for whom this information was available, 78%; median, five days; range, 0-34 days), and 136 of 197 feticides (69%) were undertaken within seven days of the initial maternal-fetal medicine review. CONCLUSIONS: Most late pregnancy feticides were performed because of fetal indications, primarily structural malformations or genetic abnormalities. Despite advances in prenatal imaging and diagnosis, late termination of pregnancy remains a necessary option in some pregnancies with maternal or fetal indications, and equitable access to late termination of pregnancy services is a vital component of reproductive health care.

Molecular Support for Heterogonesis Resulting in Sesquizygotic Twinning.

Sesquizygotic multiple pregnancy is an exceptional intermediate between monozygotic and dizygotic twinning. We report a monochorionic twin pregnancy with fetal sex discordance. Genotyping of amniotic fluid from each sac showed that the twins were maternally identical but chimerically shared 78% of their paternal genome, which makes them genetically in between monozygotic and dizygotic; they are sesquizygotic. We observed no evidence of sesquizygosis in 968 dizygotic twin pairs whom we screened by means of pangenome single-nucleotide polymorphism genotyping. Data from published repositories also show that sesquizygosis is a rare event. Detailed genotyping implicates chimerism arising at the juncture of zygotic division, termed heterogonesis, as the likely initial step in the causation of sesquizygosis.