Muscle strength during pregnancy and postpartum in adolescents and adults

by Maria Luiza da Silva Santos, Sabrina Gabrielle Gomes Fernandes Macêdo, Juliana Fernandes, Catherine M. Pirkle, Saionara M. A. Câmara

Adolescent childbirth is associated with worse physical function over the long-term. Differential loss of muscle strength during pregnancy and postpartum for adolescents compared to adults may be one explanation for this, but research examining these differences is lacking. The objective of this study as to assess hand grip strength and hip adduction muscle strength in adolescents and adults during pregnancy and postpartum. A prospective cohort study was carried out with adolescent (13 to 18 years) and adult (23 to 28 years) primigravid women. Assessments were performed at three timepoints: before the 16^th gestational week, during the third trimester, and between the fourth and sixth week postpartum. Hand grip strength (continuous and muscle weakness if ≤ 20.67 kgf) and hip adductor measures (continuous and muscle weakness if ≤ 13.8 kgf) were assessed using dynamometry. Generalized estimating equations modelled longitudinal relationships between muscle weakness and age group. More adolescents had hip adductor weakness than adults in the third trimester of pregnancy (62.5% vs. 31.8%, p < 0.005), which was corroborated by the longitudinal analyses. For all women, there were higher odds of hip adductor weakness in the third trimester (OR = 4.35; p< 0.001) and postpartum (OR = 9.45; p < 0.001) compared to the 16^th gestational week. No significant difference in HGS was observed between age groups or across the different timepoints. The higher proportion of hip adductor weakness among adolescents may indicate a need for resistance training during and after pregnancy and physical therapy if weakness or injury is noted.