Clinical Decisonmaking

Mode of delivery may be related to bleeding problems among very low birthweight newborns

Low birthweight (LBW) newborns (3 pounds or less) are more likely than other infants to suffer from low blood platelet counts (neonatal thrombocytopenia, NT) and intraventricular hemorrhage (IVH), and type of delivery affects this likelihood, finds a new study. Platelets play an important role in blood coagulation, with low platelets leading to thinner blood and an increased risk of IVH. In turn, IVH can lead to learning disabilities and mild neurodevelopmental problems, explains Douglas K. Richardson, M.D., M.B.A., of Harvard Medical School.

With support from the Agency for Healthcare Research and Quality (HS07015), Dr. Richardson and his colleagues prospectively studied the incidence of NT and IVH (confirmed by cranial ultrasound) and delivery method of 1,283 LBW infants admitted to 6 neonatal intensive care units (NICUs) over 21 months. Overall, 11 percent of the infants suffered from NT (platelet count less than 100x109/L).

NT was more prevalent among the smallest infants and declined with increasing birthweight (less than 750 g, 25 percent; 750-799 g, 9 percent; and 1,000-1,499 g, 7 percent). NT also occurred more often among the sickest infants and those considered small for gestational age. Nearly twice as many newborns with NT than without NT had IVH (45 vs. 24 percent), which usually occurs within the first few days of life. However, non-NT infants who were delivered vaginally had over twice the incidence of IVH as those delivered by cesarean section (36 vs. 16 percent). NT infants who were delivered vaginally had the highest incidence of IVH (63 vs. 38 percent for cesarean section).

In fact, vaginal delivery independently increased the risk of IVH by nearly 3 times and severe NT (platelets less than 50x109/L) by 11 times during an infant's first day in the NICU. Some researchers have suggested that increased pressure and cranial distortion/molding that occurs during labor and vaginal delivery may have detrimental effects and predispose neonates to IVH, but there continues to be debate over which delivery method is safer.

More details are in "Association of thrombocytopenia and delivery method with intraventricular hemorrhage among very-low-birthweight infants," by Doron J. Kahn, M.D., Dr. Richardson, and Henny H. Billett, M.D., in the January 2002 American Journal of Obstetrics & Gynecology 186, pp. 109-116.

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