Effect of Male Fetus on Twin Pregnancy Outcomes Studied
Risk of prematurity and low birth weight found to be higher if a male fetus is present
FRIDAY, Oct. 23 (HealthDay News) -- Among twin pregnancies, the presence of a male fetus is associated with worse pregnancy outcomes such as prematurity and low birth weight, according to a study in the November issue of Obstetrics & Gynecology.
Nir Melamed, M.D., from the Rabin Medical Center in Petah Tikva, Israel, and colleagues compared pregnancy outcomes among 2,744 dichorionic twin pregnancies based on fetal sex: female-female (16.1 percent), male-female (69.5 percent), and male-male (14.4 percent).
The researchers found that the risk of preterm delivery at less than 31 weeks gestation was 5.5 percent for female-female twins, 7.5 percent for male-female twins, and 9.2 percent for male-male twins. Male neonates had lower mean birth weights and growth rates when part of a male-male pair than when part of a male-female pair. The rate of respiratory and neurologic morbidity for female neonates, when part of a male-female pair, was similar to that of male neonates, but significantly higher than when part of a female-female pair.
"In twins, pregnancy outcome is enhanced when the fetus (male or female) shares the womb with a female rather than with a male co-twin," Melamed and colleagues conclude.