In a subset of the ALIFE study, which investigated the effect of aspirin alone or combined with low-molecular-weight heparin, compared to placebo, on the live birth rate in women with unexplained RM, the researchers looked at the length of time between the moment of randomisation to the moment of the first day of last menstruation before the subsequent pregnancy. 251 women were included in the subset, and the mean age at the time of diagnosing unexplained RM was 34 years. The women had all had at least two miscarriages with an upper gestational age of 20 weeks.
213 women became pregnant during the period February 2004 to July 2009. 139 had a live birth, 69 a miscarriage, two an ectopic pregnancy, two a termination of pregnancy and one had an intra-uterine foetal death. The median time to a subsequent pregnancy, irrespective of outcome, was 21 weeks. The cumulative incidence of natural conception was 56% after six months, 74% after 12 months, and 86% after 24 months of which 65% resulted in a live birth.
"These women were all randomised to receive one of the treatments or placebo, but further analysis showed that these made no difference to the outcome. Even such factors as maternal age, BMI, the number of previous miscarriages and the presence or absence of a previous live birth did not alter results significantly. Only the presence of Factor V Leiden significantly predicted a shorter time to conception," said Dr. Kaandorp. Factor V Leiden is a specific gene mutation that results in thrombophilia (an increased tendency to form abnormal clots that can block blood vessels).
"Factor V Leiden mutation was present in 11 women; 64% of the pregnancies in these women resulted in a live birth as opposed to 65% in the women who did not carry the mutation," said Dr. Kaandorp. "This mutation is usually associated with recurrent miscarriage, so finding a shorter time to pregnancy in the group carrying the mutation is very interesting and we intend to investigate it further."
The researchers now intend to follow up their work by looking at the time it took to achieve a live birth as opposed to simply time to pregnancy. "This will be important in counselling these women for their future pregnancy attempts," said Dr. Kaandorp. "We hope that our work will encourage health professionals to avoid non evidenced-based and potentially harmful treatments for couples. For example, aspirin and low-molecular-weight heparin are still being used, even though the ALIFE study showed clearly that there is no evidence that they are helpful.
"Our results mean that women with RM can be reassured that their time to a subsequent conception is not significantly longer than that for fertile women without a history of miscarriage. RM is extremely stressful for these women and we hope that our study will give them hope and encourage them to keep trying for the baby they want so much," he concluded.
Maternal health complications on the rise in Illinois, study reveals