Bringing birth forward to 39 weeks has no adverse developmental effects

A study of developmental outcomes of children birthed following an induction of labour at 39 weeks’ gestation has shown there is no difference in childhood development by ages four to six years when compared with children whose gestation reached or went beyond full-term.

As rates of induction of labour rise globally, this is reassuring for both clinicians and pregnant women. Mothers can feel assured that if they choose to bring birth forward to 39 weeks it is not only safe for them and their newborn in the short-term, but will not adversely affect their child’s long-term development. And if their baby happens to be born via caesarean section, the child will still develop well.

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The context

A report from the Australian Institute for Health and Welfare shows that in Australia, 47 per cent of all first time mum’s  labours are induced, or ‘medically kickstarted’, and most of these inductions are timed to birth the baby around 39 weeks’ gestation – a week earlier than full term.

This is a quite sudden increase in induced labour, with rates rising from 32 percent in 2010 to current levels.

The likely cause for the sharp increase in induced labours is the many clinical trials which have shown it to be very safe, medically. In fact, there are hints it could reduce the chances of emergency caesarean section and reduce adverse outcomes for the newborn.

However, a vital piece of safety data is missing for this very common intervention: the potential impact on long term childhood outcomes.

Inducing labour reduces the amount of time the baby spends in the womb and it’s possible this could adversely impact the child’s health beyond the newborn period. If reducing time in the uterus does in fact affect long term childhood development, the rise and rise of induced labours could translate to the birth of future generations who are less healthy, and less smart – which would be a serious safety concern surrounding the routine use of induction.

The study was published in JAMA Paediatrics and conducted by a group of research scientists, biostatisticians and educators from the University of Melbourne and the Royal Women's and Mercy Hospitals, led by Dr Anthea Lindquist, Dr Roxanne Hastie, Dr Richard Hiscock and Professor Stephen Tong.

Developing the solution

The research team set about to fill in this missing piece of evidence. They examined childhood developmental outcomes among four- to six-year-olds born at 39 weeks’ gestation following an induction of labour or planned caesarean section and compared them to those of children born after 39 weeks’ gestation.

The results of widespread teacher testing were used as data for the study. All pre-schoolers in Victoria are assessed by their teachers according to five important health domains that include aspects of social competence, emotional maturity, and communication skills.

These assessments go beyond a child’s ability to read and write and offer crucial insight into a child’s development. By using this data to investigate their research question, the team was able to examine childhood development through a more wholistic lens, rather than being focussed solely on educational performance.

The results were reassuring. In the cohort of 88,165 children, the 15,927 who were birthed following an induced labour were at no greater risk of being developmentally vulnerable compared to those whose gestation continued until after 39 weeks. Vulnerability was defined as scoring under the tenth percentile for two or more of the five developmental domains assessed.

Further testing for safety

Labour, induced or not, ends a few ways: a spontaneous vaginal birth, a forceps or vacuum assisted birth, or caesarean section. In fact, the number of births that follow an induced labour or caesarean section outweigh the number of spontaneous vaginal births.

To provide a more complete picture of the impact that decisions made within the birth suite have on childhood outcomes the researchers also assessed the same childhood outcomes according to how the baby was birthed.

These findings were also reassuring. By ages four to six there was no difference in developmental outcomes according to the manner of birth (forceps or vacuum assisted, caesarean section or without assistance). The findings also showed no difference for those children who were delivered at 39 weeks but went straight to caesarean section, bypassing labour completely.

People

Dr Anthea Lindquist
Senior Research Fellow - Perinatal Epidemiology, Consultant Obstetrician/Gynaecologist
Department of Obstetrics and Gynaecology, Mercy Hospital for Women

Dr Roxanne Hastie
Senior Research Fellow - Perinatal Epidemiology
Department of Obstetrics and Gynaecology, Mercy Hospital for Women

Dr Amber Kennedy
PhD candidate, Consultant Obstetrician/Gynaecologist
Department of Obstetrics and Gynaecology, Mercy Hospital for Women

Professor Lyle Gurrin
Melbourne School of Population and Global Health

Anna Middleton
Department of Obstetrics and Gynaecology, Mercy Hospital for Women

Associate Professor Jon Quach
Melbourne Graduate School of Education

Professor Jeanie Cheong
Neonatal Paediatrician, Department of Neonatal Services
Murdoch Children's Research Institute

Professor Susan P Walker
Head Of Department and Chair of Maternal Fetal Medicine
Department of Obstetrics and Gynaecology, Mercy Hospital for Women

Dr Richard Hiscock
Biostatistician - Perinatal Epidemiology
Department of Obstetrics and Gynaecology, Mercy Hospital for Women

Professor Stephen Tong
Professorial Fellow
Department of Obstetrics and Gynaecology, Mercy Hospital for Women

Publications

Anthea Lindquist*, Roxanne Hastie*, Amber Kennedy, Lyle Gurrin, Anna Middleton, Jon Quach, Jeanie Cheong, Susan P Walker, Richard Hiscock*, Stephen Tong*. Developmental outcomes for children following elective birth at 39 weeks’: causal inference analyses’ examining the timing and mode of birth. JAMA Paediatrics, 9 May 2022, doi:10.1001/jamapediatrics.2022.1165

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