Shorter Interpregnancy interval after termination of pregnancy ups the risk of preterm delivery in subsequent pregnancy.

Courtesy: www.americannursetoday.com

Women who conceive within 6 months of termination of pregnancy have a small but significant increased chance of having a preterm birth, per a recent paper published online January 09, 2017 in Obstetrics and Gynecology journal. [1]

On the other hand, longer interpregnancy interval of 18-24 months is not associated with having preterm birth, low birth weight (LBW), and small-for gestational-age (SGA) infants in the next pregnancy.

The time elapsed since last pregnancy may be one of the many factors that affects the fate of the current pregnancy. The optimum interpregnancy interval (IPI) following a delivery or miscarriage to avoid adverse pregnancy outcome has always been debated. Both longer and shorter IPI have been associated with adverse pregnancy outcome. IPI interval can be modified by women to improve the pregnancy outcome. But, to determine the role played by IPI as a single modifiable factor in pregnancy outcome is a difficult task because of multiple confounding factors.

The WHO has recommended avoiding pregnancy for 6 months after a miscarriage for a good pregnancy outcome in next pregnancy. [2]

In this register based national study carried out in Finland all women who had a termination of pregnancy (medical or surgical), between 2000 and 2009 and who had a subsequent live birth were included in the study. After excluding data on women who did not fit the study protocol, a total of 19,894 women were included in the study.

The women were divided into 5 groups based on the interval between termination and subsequent conception ending in live birth: less than 6months, 6 to less than 12 months, 12 to less than 18 months, 18 to less than 24 months and more than 24months. The group 18 to less than 24 months was taken as reference group.

Logistic regression analysis performed using SPSS 23.0 taking into account 9 demographic confounding factors like parity, prepregnancy body mass index (BMI), cohabitation, type of residence, socioeconomic status, maternal age, smoking, type of termination of pregnancy, and gestational age at termination of pregnancy.

The median interpregnancy interval was 21 months in the study group, 15% (n=52,956) of women conceived within 6 months of the termination while nearly half (45.4%) of the cohort were able to keep the interval at more than 24 months (n=59,036). 10% of the women kept the interval between 18 to 24 months and acted as reference group for the analysis.

167 (5.6%)women with an interpregnancy interval of less than 6 months had preterm delivery as compared to 83 (4.0%) in the reference group, which was statistically significant (P=.008).

The odds of woman having a preterm birth because of short interpregnancy interval was 1.44 (P=.034) as compared to control group after adjusting for all the confounding factors.

In a subgroup analysis excluding women who terminated their pregnancies because of a fetal anomaly or abnormality, the association still persisted.

Less than 6 months Interpregnancy interval did not have any effect on increased incidence of low birthweight or small for gestational age babies that remained more or less same throughout the 5 groups.

The limitation of the study is no distinction was made between spontaneous miscarriages and medical termination of pregnancy.  Ethnicity and previous H/O preterm birth could have confounded the results.

The authors concluded “Our results highlight the importance of contraception after termination of pregnancy, well-timed subsequent pregnancy may help to avoid complications associated with preterm birth.”

They stress upon the need for patient education and information of all women undergoing spontaneous or medical termination of pregnancy regarding the interpregnancy interval and risk of preterm births in subsequent pregnancies.

The full text of the article can be found here.

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[1] http://journals.lww.com/greenjournal/Abstract/publishahead/Interpregnancy_Interval_After_Termination_of.98502.aspx

[2]http://www.who.int/reproductivehealth/publications/family_planning/WHO_RHR_07_1/ en/.