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Delivering twins at 37 weeks minimizes stillbirth risk

In uncomplicated pregnancies, dichorionic twin deliveries should be considered at 37 weeks gestation, and monochorionic deliveries at 36 weeks to minimize perinatal death, according to data published in The BMJ.

“Twin pregnancies are high risk, with a thirteenfold increase in rates of stillbirth in monochorionic and a fivefold increase in dichorionic twins compared with singleton pregnancies,” Fiona Cheong-See, MBBS, of Queen Mary University, in London, and colleagues wrote. “… The optimal gestational age for delivery that minimizes fetal and neonatal complications in twin pregnancies is not known. Current recommendations vary on the timing of delivery, starting from 34 up to 37 weeks’ gestation in monochorionic twin pregnancies and from 37 up to 39 weeks in dichorionic twin pregnancies.”

To determine the risk for stillbirth and neonatal complications by gestational age among uncomplicated twin pregnancies, the researchers conducted a systematic review and meta-analysis of 32 studies, representing 29,685 dichorionic and 5,486 monochorionic pregnancies. Studies were gathered from Medline, Embase and Cochrane databases, without language restrictions, and focused on women with uncomplicated twin pregnancies that reported rates of stillbirth and neonatal outcomes at various gestational ages. Those with unclear chorionicity, monoamnionicity and twin-to-twin transfusion syndrome were excluded.

The researchers conducted meta-analysis of observational studies and cohorts nested within randomized studies. Prospective risk for stillbirth was calculated for each study at a given week, and compared with the risk for neonatal death among deliveries in the same week. Gestational age-specific variations in risk were estimated for stillbirths in pregnancies after 34 weeks.

According to the researchers, among dichorionic twin pregnancies beyond 34 weeks, representing 15 studies with 17,830 participants, the prospective weekly risk for stillbirth from expectant management and the risk for neonatal death from delivery were balanced at 37 weeks’ gestation (risk difference [RD] = 1.2/1,000; 95% CI, –1.3 to 3.6; I² = 0%). Also, delaying the delivery by a week, to 38 weeks’ gestation, led to an additional 8.8 perinatal deaths per 1,000 pregnancies, compared with the previous week (95% CI, 3.6-14/1,000; I² = 0%). Among monochorionic pregnancies after 34 weeks, representing 13 studies with 2,149 participants, there was a trend toward an increase in stillbirths compared with neonatal deaths after 36 weeks, with an additional 2.5 per 1,000 perinatal deaths, which was not significant.

In addition, the rates of neonatal morbidity consistently decreased with increasing gestational age in twin pregnancies. Admission to the ICU was the most common neonatal complication.

“Based on our findings, there is no clear evidence to recommend early preterm delivery routinely before 36 weeks in monochorionic pregnancies,” Cheong-See and colleagues wrote. “… With a 10^th of all twin pregnancies delivering before 32 weeks, our estimates on early preterm neonatal mortality and morbidity provide crucial information to counsel mothers at risk of early preterm delivery.” – by Jason Laday

Disclosure: The researchers report no relevant financial disclosures.