Association between timing and duration of breech presentation during pregnancy and developmental dysplasia of the hip: A case-control study

This case-control study investigated the association between timing and duration of breech presentation in pregnancy and developmental dysplasia of the hip (DDH). Children with DDH aged 3 years or younger ( n = 191) were compared with healthy controls ( n = 209). Data on outcome, exposure and, covariates were collected using a parents’ self-report online questionnaire. Term children with breech presentation at one or more check-ups after 30.0 weeks gestation had a twofold higher risk of developing DDH compared to children who had never presented in breech (OR 2.01; 95% CI [1.28, 3.15]). The strength of the association increased with duration of breech presentation (5–8 weeks: OR 2.65; 95% CI [1.36, 5.18]; 9–12 weeks: OR 3.63; 95% CI [1.82, 7.24]). Children who had presented in breech at least once in gestational period 37.0-birth had a 3.24 (95% CI [1.86, 5.65]) times higher risk of DDH, whereas the risk for children with breech presentation in gestational period 30.0–36.6 only was not increased. Also after adjusting for confounders, children who had presented in breech after gestational week 37.0-birth had a more than threefold higher risk of DDH (OR 3.33; 95% CI [1.81, 6.13]) compared to children who were never in breech or in gestational period 30.0–36.6 only