Australia: Study on Birth at 39 Weeks Gestation

A cohort study of 155,000 births revealed that birth at 39 weeks gestation does not impact primary school educational outcomes compared to birth at 40 to 42 weeks. The findings were published online in JAMA Network Open on November 17, 2023.

Birth at 39 weeks is becoming frequent, and this trend is likely to be associated with the findings of the ARRIVE trial published in 2018. This randomized clinical trial (RCT) revealed that bringing forward to 39 weeks gestation via labour induction lowered the rates of cesarean delivery and improved maternal experience of birth, raising the risk of adverse perinatal outcomes.

Birth at 39 weeks gestation is suggested to be safe for the mother and neonate. However, findings of long-term outcomes for children born at this gestational age have been conflicting. Therefore, Richard J. Hiscock, Mercy Perinatal, Mercy Hospital for Women, Heidelberg, Victoria, Australia, and colleagues aimed to evaluate the association of birth at 39 weeks gestation with childhood literacy and numeracy scores at ages 7 to 9 years compared with birth at 40 to 42 weeks gestation.

In the Australian statewide, population-based study, the researchers used a causal inference framework based on target trial emulation to link perinatal data on births between 2005 and 2011 to educational outcomes at 7 to 9 years of age. The study population included 155,575 children. Of these children, 49,456 (31.8%; 50.5% were boys) were born at 39 weeks gestation and were compared with 106,119 (68.2%; 49.1% boys) born at 40 to 42 weeks gestation.

Literacy and numeracy outcomes were assessed at age 7 to 9 years using Australian National Assessment Program–Literacy and Numeracy data and defined by overall z score across five domains (reading, grammar and punctuation, spelling, writing, and numeracy). Population average causal effects were estimated using multiple imputations and doubly robust inverse probability weighted regression adjustment.

Findings

• Birth at 39 weeks gestation was not associated with altered educational outcomes for children aged 7 to 9 years compared with their peers born at 40 to 42 weeks gestation (mean [SE] z score, 0.0008 vs –0.0031).
• Each educational domain was investigated, and no significant difference was found in:
  • Grammar and punctuation (risk difference [RD], −0.006)
  • Spelling (RD, 0.001)
  • Numeracy (RD, −0.009)
  • Reading (RD, −0.008)
  • Writing (RD, 0.006)
• Birth at 39 weeks gestation also did not increase the risk of scoring below national minimum standards in any of the 5 tested domains.

"These findings provide reassurance to clinicians and families that planned birth at 39 weeks gestation was not associated with advanced primary school-aged educational achievement," the researchers concluded.

Reference

Hiscock RJ, Atkinson JA, Tong S, et al. Educational Outcomes for Children at 7 to 9 Years of Age After Birth at 39 vs 40 to 42 Weeks’ Gestation. JAMA Netw Open. 2023;6(11):e2343721. doi:10.1001/jamanetworkopen.2023.43721