Jon Barrett

BACKGROUND: Maternal serum markers used for trisomy 21 screening are associated with placenta-mediated complications. Recently, there has been a transition from the traditional first-trimester screening (FTS) that included PAPP-A (pregnancy-associated plasma protein-A) and beta-hCG (human chorionic gonadotropin), to the enhanced FTS test, which added first-trimester AFP (alpha-fetoprotein) and PlGF (placental growth factor). However, whether elevated first-trimester AFP has a similar association with placenta-mediated complications to that observed for elevated second-trimester AFP remains unclear. Our objective was to estimate the association of first-trimester AFP with placenta-mediated complications and compare it with the corresponding associations of second-trimester AFP and other first-trimester serum markers. METHODS: Retrospective population-based cohort study of women who underwent trisomy 21 screening in Ontario, Canada (2013–2019). The association of first-trimester AFP with placenta-mediated complications was estimated and compared with that of the traditional serum markers. The primary outcome was a composite of stillbirth or preterm placental complications (preeclampsia, birthweight less than third centile, or placental abruption). RESULTS: A total of 244 990 and 96 167 women underwent FTS and enhanced FTS test screening, respectively. All markers were associated with the primary outcome, but the association for elevated first-trimester AFP (adjusted relative risk [aRR], 1.57 [95% CI, 1.37–1.81]) was weaker than that observed for low PAPP-A (aRR, 2.48 [95% CI, 2.2–2.8]), low PlGF (aRR, 2.28 [95% CI, 1.97–2.64]), and elevated second-trimester AFP (aRR, 1.97 [95% CI, 1.81–2.15]). When the models were adjusted for all 4 enhanced FTS test markers, elevated first-trimester AFP was no longer associated with the primary outcome (aRR, 0.77 [95% CI, 0.58–1.02]). CONCLUSIONS: Unlike second-trimester AFP, elevated first-trimester AFP is not an independent risk factor for placenta-mediated complications.

Mode of delivery in twin gestation has been a matter of debate for decades. In 2013, the only randomized controlled trial concerning mode of delivery in twin gestations was published, answering some of the most pressing questions in this matter. The Twin Birth Study randomized patients carrying dichorionic-diamniotic or monochorionic-diamniotic twins, with the first twin in cephalic presentation, between 32 and 39 weeks of gestation, to planned vaginal vs. planned cesarean delivery, and found no significant differences in perinatal or maternal outcomes. These clinical findings greatly benefit our clinical practice, but there lacks related study investigating how the practices have changed. In this review, we searched PubMed from 1980 through January 2021 using combinations of the following terms: twin, delivery, vaginal delivery, and Cesarean section. We will try to address the known literature before and after the publication of the Twin Birth Study in western countries and compare that to what has been practiced in China.