Offering universal late pregnancy ultrasounds at 36 weeks’ gestation eliminates undiagnosed breech presentation of babies, lowers the rate of emergency caesarean sections, and improves the health of mothers and babies. These are some of the conclusions of the Pregnancy Outcome Prediction study led by researchers at the University of Cambridge.
Undiagnosed breech presentation – when a baby’s buttocks or feet emerge first at birth – increases the risk of perinatal morbidity and mortality. In current practice, foetal presentation is assessed by palpation of the maternal abdomen, but the sensitivity of this approach varies by practitioner. By routinely using ultrasound screening, undiagnosed breech presentation in labour could be avoided, lowering the risk of morbidity and mortality for both mother and baby.
In the new study, researchers performed research screening ultrasounds at 36 weeks’ gestation in 3,879 women having first pregnancies in England. A total of 179 women (4.6%) were diagnosed with breech presentation by the research scan. However, in over half of these cases (55%) there was no prior suspicion that the baby was presenting in the breech position.
Making the diagnosis at 36 weeks allowed women to opt for an attempt at turning the baby, called external cephalic version. For the women who declined this procedure, or where it was unsuccessful, a planned caesarean section was arranged. None of the women opted to attempt a vaginal breech birth, which is known to be associated with an increased risk of complications, particularly in first pregnancies.
Across the UK, the analysis estimated that routine scanning could prevent around 15,000 undiagnosed breech presentations, more than 4,000 emergency caesarean sections and 7 to 8 baby deaths per year. If a scan could be done for less than £12.90 then it could be cost-saving to the NHS. This could be possible once midwives are instructed how to perform the simple technique, using inexpensive portable equipment.
Professor Gordon Smith from the department of obstetrics and gynaecology at the University of Cambridge, who led the study, said: “We believe the study highlights an opportunity to identify women at increased risk of a complicated birth. It seems likely that screening for breech presentation near term could be introduced in a cost-effective manner and this should be considered by the National Health Service (NHS) and other health systems.”
The research was funded by the National Institute for Health Research.
Background: Despite the relative ease with which breech presentation can be identified through ultrasound screening, the assessment of foetal presentation at term is often based on clinical examination only. Due to limitations in this approach, many women present in labour with an undiagnosed breech presentation, with increased risk of foetal morbidity and mortality. This study sought to determine the cost effectiveness of universal ultrasound scanning for breech presentation near term (36 weeks of gestational age [wkGA]) in nulliparous women.
Methods and findings: The Pregnancy Outcome Prediction (POP) study was a prospective cohort study between January 14, 2008 and July 31, 2012, including 3,879 nulliparous women who attended for a research screening ultrasound examination at 36 wkGA. Foetal presentation was assessed and compared for the groups with and without a clinically indicated ultrasound. Where breech presentation was detected, an external cephalic version (ECV) was routinely offered. If the ECV was unsuccessful or not performed, the women were offered either planned cesarean section at 39 weeks or attempted vaginal breech delivery. To compare the likelihood of different mode of deliveries and associated long-term health outcomes for universal ultrasound to current practice, a probabilistic economic simulation model was constructed. Parameter values were obtained from the POP study, and costs were mainly obtained from the English National Health Service (NHS). One hundred seventy-nine out of 3,879 women (4.6%) were diagnosed with breech presentation at 36 weeks. For most women (96), there had been no prior suspicion of noncephalic presentation. ECV was attempted for 84 (46.9%) women and was successful in 12 (success rate: 14.3%). Overall, 19 of the 179 women delivered vaginally (10.6%), 110 delivered by elective cesarean section (ELCS) (61.5%) and 50 delivered by emergency cesarean section (EMCS) (27.9%). There were no women with undiagnosed breech presentation in labour in the entire cohort. On average, 40 scans were needed per detection of a previously undiagnosed breech presentation. The economic analysis indicated that, compared to current practice, universal late-pregnancy ultrasound would identify around 14,826 otherwise undiagnosed breech presentations across England annually. It would also reduce EMCS and vaginal breech deliveries by 0.7 and 1.0 percentage points, respectively: around 4,196 and 6,061 deliveries across England annually. Universal ultrasound would also prevent 7.89 neonatal mortalities annually. The strategy would be cost effective if foetal presentation could be assessed for £19.80 or less per woman. Limitations to this study included that foetal presentation was revealed to all women and that the health economic analysis may be altered by parity.
Conclusions: According to our estimates, universal late pregnancy ultrasound in nulliparous women (1) would virtually eliminate undiagnosed breech presentation, (2) would be expected to reduce foetal mortality in breech presentation, and (3) would be cost effective if foetal presentation could be assessed for less than £19.80 per woman.
David Wastlund, Alexandros A Moraitis, Alison Dacey, Ulla Sovio, Edward CF Wilson, Gordon CS Smith