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Advise a year between pregnancies after preterm birth

Shorter interval strongly linked to having another preterm birth and low birth weight

Louise Prime

Wednesday, 04 February 2015

Doctors should counsel women who’ve had a preterm birth to wait at least 12 months before they attempt to conceive again, to reduce their risk of problems in a subsequent pregnancy, advise researchers. Their work*, being presented in the US tomorrow at the annual meeting of the Society for Maternal-Fetal Medicine, showed that women who were pregnant again less than a year after a preterm birth were much more likely than those who waited longer, to have another baby severely preterm or of low birth weight.

It was already known that women who’ve given birth preterm are at greater than average risk of doing so again; these researchers, from The Netherlands and Australia, wanted to investigate the effect of the length of time between giving birth and conceiving again, on several outcomes in the second pregnancy – birth before 30 weeks, birth before 37 weeks and birth weight below 2500g. They analysed data for 1999-2007 from the National Perinatal Registry in the Netherlands, on 11,535 women who had had spontaneous preterm birth (before 37 weeks) in their first pregnancy, excluding pregnancies complicated by congenital abnormalities, multiple births, stillbirth or primary caesarean section.

They reported that in women who had suffered a previous preterm birth, variation of the interval between that delivery and conception of the next pregnancy had a strong impact on the risk of both preterm birth and birth weight in the next pregnancy. An interval of less than 12 months was associated with an increased risk for severe preterm birth in women who already suffered preterm birth in their first pregnancy.

The researchers commented: “This information should be considered in counselling women with preterm birth in their medical history ... Women with preterm birth are advised to postpone their next pregnancy for at least 12 months to prevent another preterm birth.”

Authors of a separate study** from the same research centres found that male babies are at greater risk than females, both of spontaneous preterm birth and of preterm premature rupture of membranes, i.e. between 26 and 37 weeks. They suggested that women with a history of preterm birth should be monitored, particularly if they are now carrying a boy after a preterm birth of a girl.


* Bouchra Koullali, et al. Can variation of the interval between the first and second pregnancy be used as a therapeutic strategy to reduce recurrent spontaneous preterm birth?

** Myrthe Peelen, et al. Impact of Fetal Gender on the Risk of Preterm Birth.

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