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Risk of major labour-related complications for pregnancies progressing to 42 weeks or beyond.

Authors :
Lindquist AC
Hastie RM
Hiscock RJ
Pritchard NL
Walker SP
Tong S
Source :
BMC medicine [BMC Med] 2021 May 25; Vol. 19 (1), pp. 126. Date of Electronic Publication: 2021 May 25.
Publication Year :
2021

Abstract

Background: Post-term gestation beyond 41 <superscript>+6</superscript> completed weeks of gestation is known to be associated with a sharp increase in the risk of stillbirth and perinatal mortality. However, the risk of common adverse outcomes related to labour, such as shoulder dystocia and post-partum haemorrhage for those delivering at this advanced gestation, remains poorly characterised. The objective of this study was to examine the risk of adverse, labour-related outcomes for women progressing to 42 weeks gestation or beyond, compared with those giving birth at 39 completed weeks.<br />Methods: We performed a state-wide cohort study using routinely collected perinatal data in Australia. Comparing the two gestation cohorts, we examined the adjusted relative risk of clinically significant labour-related adverse outcomes, including macrosomia (≥ 4500 at birth), post-partum haemorrhage (≥1000 ml), shoulder dystocia, 3rd or 4th degree perineal tear and unplanned caesarean section. Parity, maternal age and mode of birth were adjusted for using logistic regression.<br />Results: The study cohort included 91,314 women who birthed at 39 completed weeks and 4317 at ≥42 completed weeks. Compared to 39 weeks gestation, those giving birth ≥42 weeks gestation had an adjusted relative risk (aRR) of 1.85 (95% CI 1.55-2.20) for post-partum haemorrhage following vaginal birth, 2.29 (95% CI 1.89-2.78) following instrumental birth and 1.44 (95% CI 1.17-1.78) following emergency caesarean section; 1.43 (95% CI 1.16-1.77) for shoulder dystocia (for non-macrosomic babies); and 1.22 (95% CI 1.03-1.45) for 3rd or 4th degree perineal tear (all women). The adjusted relative risk of giving birth to a macrosomic baby was 10.19 (95% CI 8.26-12.57) among nulliparous women and 4.71 (95% CI 3.90-5.68) among multiparous women. The risk of unplanned caesarean section was 1.96 (95% CI 1.86-2.06) following any labour and 1.47 (95% CI 1.38-1.56) following induction of labour.<br />Conclusions: Giving birth at ≥42 weeks gestation may be an under-recognised risk factor for several important, labour-related adverse outcomes. Clinicians should be aware that labour at this advanced gestation incurs a higher risk of adverse outcomes. In addition to known perinatal risks, the risk of obstetric complications should be considered in the counselling of women labouring at post-term gestation.

Details

Language :
English
ISSN :
1741-7015
Volume :
19
Issue :
1
Database :
MEDLINE
Journal :
BMC medicine
Publication Type :
Academic Journal
Accession number :
34030675
Full Text :
https://doi.org/10.1186/s12916-021-01988-5