Pre-term Pregnancies

Spring fling may lead to early births . . .

Women who become pregnant in the Spring may be more likely to deliver their babies before 37 weeks gestation than those that conceive at other times of the year.

Drs. Lisa M. Bodnar and Hyagriv N. Simhan of the University of Pittsburgh Medical Center studied the records of 75,399 women who delivered at Magee-Women’s Hospital over the 10-year period 1995 to 2005. They grouped the women by season of last menstrual period, used to estimate time of conception.

Babies were more likely to be born early among women who became pregnant in the spring and less likely to those that conceived in the summer.

The rate for early birth, or preterm births were 8.4 percent for those who got pregnant in the summer and 8.8 for fall pregnancies, 9.1 percent for winter pregnancies and 9.2 percent for spring pregnancies.

The rate for birth before 32 weeks was also lowest with summer pregnancies at 2 percent with increasing rates for fall at 2.3 percent, winter 2.5 percent and spring at 2.7 percent.

Reasons given for seasonal differences in preterm delivery include seasonal allergens, viral infections, as well as perhaps seasonal dietary changes, sunlight exposure and exercise habits.

Dr. Simhan presented the study findings this week in San Francisco at the meeting of the Society of Maternal-Fetal Medicine.