NEW YORK (Reuters Health) - Women who bleed early in pregnancy but don't miscarry are at increased risk of pregnancy complications, and this risk carries over to their next pregnancy, according to a large new study from Denmark.
The findings suggest that doctors should keep a closer eye on pregnant women who have experienced first-trimester vaginal bleeding, conclude Dr. Jakob Alexander Lykke of Roskilde Hospital in Roskilde and his colleagues.
It's been shown that about half of women who have first-trimester bleeding will miscarry by 20 weeks of pregnancy, while women who bleed but don't miscarry are known to be more likely to have pregnancy complications. In the current study, the researchers investigated whether this risk might persist into a woman's next pregnancy.
They looked at records for nearly 800,000 Danish women who delivered a first baby between 1978 and 2007, and a subset of nearly 540,000 of these women who also had a second child during that time period.
Around 2 percent of women in both groups had first-trimester bleeding during their pregnancies. Among women who had bleeding in their first pregnancies, 6 percent delivered their babies early between 32 and 36 weeks' gestation, compared to about 4 percent of the women who had no bleeding. (Babies born at 37 weeks of pregnancy or later are considered full-term.)
Earlier preterm delivery, at 28 to 31 weeks, was also more common in women with bleeding (0.3 percent vs. 0.9 percent), as was a pregnancy complication called placental abruption (1.0 percent vs. 1.4 percent), in which the placenta separates from the uterus before delivery.
In addition, premature rupture of membranes, in which water breaks before labor begins in a woman who is at least 37 weeks' pregnant, occurred in 6 percent of women with first-trimester bleeding and 5 percent of women with no bleeding.
According to the researchers, women who bled early in their first pregnancy but not in their second pregnancy were still at increased risk in their subsequent pregnancy for preterm delivery and premature membrane rupture; 8.2 percent of these women delivered their babies at 32 to 36 weeks of pregnancy, compared to 2.2 percent of women with no bleeding; risks for earlier preterm delivery were 4.8 percent and 2.7 percent, respectively.
Four percent of women who had experienced first-trimester bleeding in their first pregnancy had premature rupture of membranes in their second pregnancy, compared to 3 percent of women who did not have bleeding.
The researchers conclude, based on their observations, that early pregnancy bleeding, preterm delivery, placental abruption and premature rupture of membranes may be related to one another, and could provide clues to the underlying causes of these complications.
SOURCE: Obstetrics & Gynecology, May 2010.