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Planned caesareans 'safer' for women with past history of caesarean sections

25 September 2019

"Planned caesarean delivery can be the safest option for women who have had a caesarean in the past," BBC News reports.

A new study of around 74,000 births in Scotland suggested that women who'd previously had a caesarean section were more likely to have problems if they attempted a vaginal delivery in subsequent pregnancies, rather than have a repeat caesarean. However, the study authors stressed the absolute risk of serious problems from either choice is small.

Researchers found 1.8% of women who had a planned vaginal delivery following a previous caesarean (planned VBAC) and 0.8% of those who had an elective repeat caesarean section (ERCS) had serious health problems around birth, such as significant damage to the womb.

There were also slightly more problems for babies born after planned VBAC, with 7.99% of these babies having one of a range of health problems around birth such as needing medicine or equipment to help with breathing, compared to 6.37% of those born after ERCS.

Reassuringly, the levels of stillbirths and neonatal deaths after planned VBAC recorded in the study were extremely low, with only 20 cases out of 28,499 deliveries.

Also, complications affecting mothers remained rare. For example, rupture of the womb – perhaps one of the most common concerns after a previous caesarean – occurred in around 1 in 500 vaginal deliveries.

Currently, women who have previously had a caesarean can plan for either a repeat caesarean or a vaginal birth. Women and their doctors should discuss the relative risks and benefits of either option, as well as the mother's preferences and priorities.

Find out more about making a birth plan.

Where did the story come from?

The researchers who carried out the study were from the University of Oxford and the University of Aberdeen. The study was published in the peer-reviewed journal PLOS Medicine on an open-access basis, so it is free to read online.

The headlines in some UK media overstated the risks and the advice to pregnant women. Mail Online headline warned: "Mothers who have a baby through a C-section may face a greater risk of dangerous complications if they try to give birth naturally the next time", which is not consistent with current recommendations. There is certainly no blanket recommendation telling women who've previously had a caesarean not to plan for a vaginal birth in a subsequent pregnancy.

However, the actual article in Mail Online included the appropriate advice from the researchers that "mothers should not be afraid of choosing a vaginal birth if they want to and are able to accept the risks."

What kind of research was this?

This was a cohort study. Cohort studies are a good way to look at the relationship between risk factors (such as method of giving birth) and outcomes for the mother and baby. But they do not tell us for sure that one type of delivery will be safer for any individual.

Other individual factors related to the mother's health and pregnancy might also be important and indicate one delivery choice may have been preferable to the other.

What did the research involve?

Researchers used 6 health databases in Scotland to identify 74,043 single (not twin or more) births, between 2002 and 2015, to women who had previously given birth by caesarean, and had no medical restrictions on their choice of planned delivery.

They looked at a range of health outcomes for mothers and babies. For mothers, they looked at:

  • rupture of the womb (uterine rupture) which can cause major blood loss and is dangerous for mother and baby
  • need for a blood transfusion
  • post-birth sepsis (infection)
  • surgical injury to the vagina, bowel or urinary system

For babies, they looked at:

  • stillbirth or death during birth
  • admission to a neonatal special care unit
  • need for resuscitation
  • poor health score (Apgar score less than 7) 5 minutes after birth

They took account of several confounding factors that could affect the outcomes, including the mother's age, body mass index (BMI) and smoking status, how many times she had given birth previously via caesarean section or vaginal birth, and length of time between pregnancies. They also looked into whether induction of labour affected the results.

What were the basic results?

Of the women in the study, 45,579 chose an elective repeat caesarean section (ERCS), while 28,464 chose a planned vaginal birth (VBAC). Of women choosing a planned VBAC, 71.6% were able to give birth vaginally, while 28.4% needed an emergency caesarean during labour.

Outcomes for women

  • 0.24% of women planning a VBAC and 0.04% of women planning an ERCS had a rupture of the womb, representing a 7-times increased risk with VBAC (relative risk (RR) 7.33, 95% confidence interval (CI) 3.88-13.88)
  • 1.14% of women planning a VBAC and 0.5% of women planning an ERCS needed a blood transfusion, representing a 2-times increased risk with vaginal birth (RR 2.29, 95% CI 1.88-2.79)
  • other complications such as sepsis were rare
  • looking at maternal problems overall, 1.8% of women planning a VBAC and 0.8% of those planning an ERCS had serious complications

Outcomes for babies

  • 0.01% of babies born to women planning an ERCS and 0.07% of babies born to women planning a VBAC died (RR 6.59, 95% CI 2.43-17.87)
  • 0.33% of babies born to women planning an ERCS and 1.63% of babies born to women planning a VBAC needed resuscitation at birth (RR 5.22, 95% CI 4.19-6.50)
  • 0.42% of babies born to women planning an ERCS and 1.44% of babies born to women planning a VBAC had a low Apgar score 5 minutes after birth (RR 3.84, 95%CI 3.15-4.68)
  • 5.27% of babies born to women planning an ERCS and 5.45% of babies born to women planning a VBAC were admitted to a neonatal unit (RR 1.21, 95% CI 1.22-1.41)
  • looking at overall problems for babies, 7.99% of babies born to women planning a VBAC and 6.37% of babies born to women planning an ERCS had one of a range of problems (RR 1.57, 95% CI 1.46-1.68).

Women were more likely to breastfeed after vaginal birth than after a caesarean birth, and less likely to have a long stay in hospital.

How did the researchers interpret the results?

The researchers said: "Among women considered eligible to have a planned VBAC, planned VBAC compared to ERCS is associated with an increased risk of the mother having serious birth-related maternal and perinatal [around the time of birth] complications."

They add: "However, the absolute risk of adverse maternal and perinatal outcomes was found to be small for either delivery approach."

Conclusion

The decision about whether to plan for a caesarean or a vaginal birth after a caesarean is not easy. Women and health professionals need to discuss the mother's preferences and individual circumstances, as well as the relative risks and benefits of each option.

This study is helpful in adding more information to help with that decision. However, there are some points to consider.

The study did not look at all possible outcomes, including the possibility of rare problems with the placenta after repeated caesareans (where it adheres too strongly to the womb muscle).

While the researchers tried to account for various pregnancy factors that might affect outcomes, it's not always possible to account for all of them. Other health and lifestyle factors may be relevant.

It's important to highlight that most of the health problems for women occurred among those who had planned for a vaginal birth but needed an emergency caesarean during labour. Emergency caesareans carry higher risk of complications than planned (elective) ones. The 71% of women who gave birth vaginally were less likely to have these problems.

The study also showed some benefits of vaginal birth, such as being more likely to be able to breastfeed shortly after birth and having a shorter hospital stay.

NICE guidelines state that for women who have had 4 or fewer caesareans, "the risk of fever, bladder injuries and surgical injuries does not vary with planned mode of birth" and that "the risk of uterine rupture, although higher for planned vaginal birth, is rare" – as this study confirmed.

Find out more about caesarean sections and vaginal birth.