Optimal Gestational Age for Twin Delivery

The results of a new study conducted in Australia, New Zealand, and Italy suggest that women who are pregnant with twins should elect to give birth at 37 weeks to avoid complications.¹ Much controversy surrounds whether the optimal time for twin delivery is early (37 weeks) or late (38 weeks or more); the available evidence does not provide a definitive answer.

In this new study, 235 women with an uncomplicated twin pregnancy were randomized to either elective birth at 37 weeks (116 women) or continued expectant management with planned birth on or after 38 weeks, or standard care (119 women). Elective birth at 37 weeks was associated with a significantly reduced risk of serious adverse outcomes for the neonate (4.7% vs 12.2% for standard care). In addition, elective birth at 37 weeks was associated with a reduced rate of newborns being small for gestational age (3.0% vs 10.1% for standard care).

In twin pregnancy, the slowing growth rate as the pregnancy continues can result in low birth weight, which is associated with an increased risk of heart disease and diabetes later in life, according to the lead study author Jodie Dodd, PhD, who acknowledges the uncertainty in clinical practice regarding optimal timing for twin delivery.

There has been varied evidence about when to deliver twins in an uncomplicated pregnancy for optimal outcomes. Some recommend that the optimal gestational age for delivery in uncomplicated twin pregnancies (dichorionic/diamniotic) is 38 weeks to 40 weeks.^2,3 This delivery timeframe has been determined to best avoid neonatal complications, such as fetal growth restriction, respiratory distress syndrome, sepsis, hypoglycemia, and requirements for the neonatal intensive care unit. In addition, one study showed that twins who were delivered electively had worse outcomes than those delivered spontaneously.²

Others recommend elective delivery at 37 weeks, citing that delivery at 37 weeks does not increase the risk of serious adverse effects and that continuing the pregnancy beyond 38 weeks increases the risk of fetal death.⁴ The results of this new study support this recommendation.

Pertinent Point:
- At 37 weeks gestation, elective birth is associated with a significant reduction in the risk of serious morbidity for infants without increasing complications related to immaturity or induction of labor, according to the largest study to date that addresses the timing of birth in uncomplicated twin pregnancies.
 

References:

1. Dodd J, Crowther C, Haslam R, Robinson J, for the Twins Timing of Birth Trial Group. Elective birth at 37 weeks of gestation versus standard care for women with an uncomplicated twin pregnancy at term: the Twins Timing of Birth Randomised Trial. BJOG. 2012 Jun 13. [Epub ahead of print.]
2. Bakr AF, Karkour T. What is the optimal age for twin delivery. BMC Pregnancy Childbirth. 2006;6:3.
3. Spong CY, Mercer BM, D’alton M, et al. Timing of indicated late-preterm and early-term birth. Obstet Gynecol. 2011;118:323.
4. National Institute for Health and Clinical Excellence. Multiple pregnancy: the management of twin and triplet pregnancies in the antenatal period. September 2011. Available at: http://www.nice.org.uk/nicemedia/live/13571/56422/56422.pdf. Accessed June 21, 2012.