HealthDay News — All women have a decrease in mean platelet counts during pregnancy, according to a study published in the July 5 issue of the New England Journal of Medicine.
Jessica A. Reese, PhD, from the University of Oklahoma Health Sciences Center in Oklahoma City, and colleagues examined platelet counts throughout pregnancy in 7,351 women who delivered between 2011 and 2014. Platelet counts were compared with those of non-pregnant women included in the National Health and Nutrition Examination Survey from 1999 through 2012.
The researchers found that 4,568 women had uncomplicated pregnancies, 2,586 had pregnancy-related complications, and 197 had pre-existing disorders associated with thrombocytopenia. The mean platelet count in the first trimester was 251,000/mm³ among women with uncomplicated pregnancies, compared with the mean platelet count of 273,000/mm³ among the 8,885 non-pregnant women (P < 0.001). Overall, 9.9% of women with uncomplicated pregnancies had a platelet count below 150,000/mm³ at the time of delivery. Only 45 women (1%) had a platelet count below 100,000/mm³ during the course of the uncomplicated pregnancies and deliveries. Women who had pregnancy-related complications more often had platelet counts of less than 150,000/mm³ at the time of delivery than women with uncomplicated pregnancies (11.9 vs 9.9%).
“Mean platelet counts decreased during pregnancy in all the women, beginning in the first trimester,” the authors write.