How do physical activity levels differ in twin and singleton pregnancies?

Abstract Background Twin pregnancy has been a contraindication to physical activity. Therefore, we lack population-based data describing physical activity in these pregnancies. We aimed to describe physical activity in women with twin and singleton pregnancies from pre-pregnancy through pregnancy and up to 18 months after birth. Methods We used a population-based cohort including 1,938 twin and 109,370 singleton pregnancies in the Norwegian Mother, Father and Child Cohort Study (1999-2008). Frequency of 14 different types of leisure-time physical activities (LTPA) were self-reported using a validated questionnaire in pregnancy weeks 17 and 30 and at six and 18 months after birth. We performed descriptive statistics, including median weekly frequency of LTPA with interquartile range (IQR), and proportions of women reporting LTPA at least once weekly by plurality. Preliminary results LTPA in women pregnant with twins declined from 4.00 times weekly (IQR: 2.50-6.25) pre-pregnancy to 2.25 times weekly (1.00-3.00) in pregnancy week 30. Corresponding frequencies for women with singletons were 4.00 (2.25-6.25) and 3.00 (1.25-4.25). The proportion of women reporting LTPA at least once weekly only differed in twin compared to singleton pregnancies in week 30, 61% and 70% respectively. In week 30, 10% of women pregnant with twins reported no LTPA compared to 3% of women with singletons. Eighteen months after birth, both women delivering twins and singletons resumed pre-pregnancy levels of LTPA. The most common types of LTPA were strolling and brisk walking in both groups of women. Conclusions Patterns and types of LTPA were similar in women with twin and singleton pregnancies, except in pregnancy week 30 where levels of LTPA were lower in women carrying twins. This is the first population-based study on LTPA in women pregnant with twins. Thus, we need knowledge on who remains physically active, why physical activity changes, and potential consequences of physical activity in twin pregnancy. Key messages • Women pregnant with twins were less physically active compared to women pregnant with singletons late in pregnancy. • Identifying physically inactive women and potential consequences of the decline in physical activity in women pregnant with twins is needed.