Does the interpregnancy interval affect pregnancy outcomes following a previous pregnancy loss?

This study explored the effects of a short interpregnancy interval (IPI) between a pregnancy loss and another successful pregnancy. The study concluded that there were no adverse pregnancy outcomes resulting from a very short IPI.

Pregnancy loss occurs in about 10-15% of pregnancies, mainly around the ten week mark. After pregnancy loss, couples want to know how long to wait before attempting pregnancy again. This length of time can be very important for woman who are older or who have experienced fertility problems.

The optimal length of time to wait between a pregnancy loss and trying to conceive again is not known, though the usual recommendation from doctors is to wait at least three months. The World Health Organization (WHO) recommends a minimum IPI of six months after a pregnancy loss (miscarriage or abortion). 

This study included 677 women actively trying to get pregnant. The average time of the previous pregnancy loss was at 8.6 weeks. The interpregnancy interval was the time between the last pregnancy loss and the last menstrual period of the current pregnancy. Of these women, 2.7% became pregnant within the first month, 33.2% became pregnant within three months, and 65.7% became pregnant within six months. The average IPI was 4.3 months.

The overall live birth rate was 76.5%. This was similar for an IPI less than 3 months or more than 3 months.  Pregnancy loss during the study occurred around 10 weeks. Women with longer IPIs tended to have lower rates of live births, but rates were not significantly different from shorter IPIs.

The study concluded that live birth rates and poor pregnancy outcomes were not associated with a very short IPI after pregnancy loss. The recommendation to wait more than three months to try again may not be necessary. The authors noted that this may be helpful where the woman wishes to avoid delays in becoming pregnant due to age, medical issues, or infertility.

This study was not primarily designed and powered to answer this question. This is a secondary outcome from a study asking a different research question.