Uterine surgery before a first birth is linked to preterm birth and stillbirth

Design

Population-based record-linkage cohort, New South Wales, 2007–2019

Population

520,050 women with a first birth; 14.7% had prior uterine surgery

Primary outcome

Preterm birth and stillbirth in the first birth

Effect

Preterm birth aOR 1.51 (95% CI 1.47–1.55); stillbirth aOR 1.39 (1.26–1.53)

A population record-linkage study from New South Wales followed all 520,050 women with a first birth between 2007 and 2019, and linked them to hospital records of uterine procedures from 2001. About one in seven (14.7%) had had uterine surgery before that first birth. It was published in April.

Prior uterine surgery was associated with preterm birth (adjusted odds ratio 1.51) and stillbirth (adjusted odds ratio 1.39). The associations grew with repeated procedures and were strongest at the earliest gestations. The authors describe the study as hypothesis-generating: the reason for surgery (miscarriage, fibroids, subfertility) may itself carry pregnancy risk, and the data cannot separate the two.

In practice this is a prompt at both ends. Before a procedure in a woman who may want children, weigh whether a medical alternative exists and whether the operation is needed. At booking, ask about every previous uterine procedure, not only caesarean section, and record how many there were.

• Ask at booking about every prior uterine procedure: surgical evacuation, hysteroscopy, myomectomy, septum resection.
• Record the number of procedures; associations with preterm birth rose with each repeat.
• Consider medical management of miscarriage where it is suitable and the woman prefers it.
• Consider preterm-birth surveillance for women with several prior procedures, as the authors suggest.
• Explain that this is an association, not proof that the surgery caused the outcome.

Why it matters

Procedures often treated as minor may carry weight into a first pregnancy, and they are rarely asked about.

Don't overread it

This was observational; the reason for surgery may explain part of the risk.

The statistics, in plain English

An adjusted odds ratio of 1.51 means the odds of preterm birth were about half as high again in women with prior uterine surgery, after allowing for measured factors. The narrow intervals (1.47 to 1.55 for preterm birth) reflect a very large sample, not freedom from bias: unmeasured confounding cannot be adjusted away.

Read the rest in the app

You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.

Get Daily Doctor — free

Scan to keep reading on your phone. No account needed to start.