Objectives: We aimed to estimate the optimal time of delivery and investigated the residual risk of fetal death after viability in otherwise uncomplicated monochorionic diamniotic twin pregnancies.
Study design: A database of 576 completed multiple pregnancies that were managed in our tertiary referral fetal medicine department between 1996 and 2007 was reviewed and the uncomplicated 111 monochorionic and the 290 dichorionic diamniotic twin pregnancies delivered after 24 weeks were selected. The rate of fetal death was derived for two-week periods starting at 24 weeks' gestation and the prospective risk of fetal death was calculated by determining the number of intrauterine fetal deaths that occurred within the two-week block divided by the number of continuing uncomplicated monochorionic twin pregnancies during that same time period.
Results: The unexpected single intrauterine deaths rate was 2.7% versus 2.8% in previously uncomplicated monochorionic and dichorionic diamniotic pregnancies, respectively. The prospective risk of unexpected stillbirth after 32 weeks of gestation was 1.3% for monochorionic and 0.8% for dichorionic pregnancies.
Conclusions: In otherwise apparently uncomplicated monochorionic diamniotic pregnancies this prospective risk of fetal death after 32 weeks of gestation is lower than reported and similar to that of dichorionic pregnancies, so does not sustain the theory of elective preterm delivery.