Objective Childbirth is suggested to be associated with elevated levels of sickness absence (SA) and disability pension (DP). However, detailed knowledge about SA/DP patterns around childbirth is lacking. We aimed to compare SA/DP across different time periods among women according to their childbirth status.

Design Register-based longitudinal cohort study.

Setting Sweden.

Participants Three population-based cohorts of nulliparous women aged 18–39 years, living in Sweden 31 December 1994, 1999 or 2004 (nearly 500 000/cohort).

Primary and secondary outcome measures Sum of SA >14 and DP net days/year.

Methods We compared crude and standardised mean SA and DP days/year during the 3 years preceding and the 3 years after first childbirth date (Y−3 to Y+3), among women having (1) their first and only birth during the subsequent 3 years (B1), (2) their first birth and at least another delivery (B1+), and (3) no childbirths during follow-up (B0).

Results Despite an increase in SA in the year preceding the first childbirth, women in the B1 group, and especially in B1+, tended to have fewer SA/DP days throughout the years than women in the B0 group. For cohort 2005, the mean SA/DP days/year (95% CIs) in the B0, B1 and B1+ groups were for Y−3: 25.3 (24.9–25.7), 14.5 (13.6–15.5) and 8.5 (7.9–9.2); Y−2: 27.5 (27.1–27.9), 16.6 (15.5–17.6) and 9.6 (8.9–10.4); Y−1: 29.2 (28.8–29.6), 31.4 (30.2–32.6) and 22.0 (21.2–22.9); Y+1: 30.2 (29.8–30.7), 11.2 (10.4–12.1) and 5.5 (5.0–6.1); Y+2: 31.7 (31.3–32.1), 15.3 (14.2–16.3) and 10.9 (10.3–11.6); Y+3: 32.3 (31.9–32.7), 18.1 (17.0–19.3) and 12.4 (11.7–13.0), respectively. These patterns were the same in all three cohorts.

Conclusions Women with more than one childbirth had fewer SA/DP days/year compared with women with one childbirth or with no births. Women who did not give birth had markedly more DP days than those giving birth, suggesting a health selection into childbirth.