But as surgical techniques changed, it became possible for many women to have a vaginal birth after caesarean (VBAC).
As doctors and patients learned more about VBAC, it became a more popular option. Current guidelines from the Society of Obstetricians and Gynaecologists of Canada recommend that women with a previous C-section be offered a trial of labour if they meet VBAC safety criteria (such as appropriate type of caesarean scar, and giving birth in a hospital where an emergency C-section is available).
For many women with a prior caesarean, VBAC became the goal for their next pregnancy. Popular wisdom had gone from one end of the spectrum (where one C-section meant another C-section) to the other end (where VBAC is best).
For VBAC, the pendulum may be swinging back to the centre as more research helps doctors highlight the risks and benefits, and select the patients most likely to have successful VBACs. Dr. Hani Akoury, a perinatologist and associate chief of obstetrics at Sunnybrook Health Sciences Centre, outlined recent VBAC research during a talk at Women’s College Hospital in Toronto on Oct. 2, 2009.
A vaginal birth is generally the most desirable option for both mother and baby, and that goes for women who have had a prior caesarean as well. If a vaginal birth is not possible or not advisable, a planned C-section is a safe alternative. However, a failed VBAC ending in an emergency caesarean is the least attractive outcome for mother and baby, with the most risks and the most potential adverse effects.
Several factors contribute to the likelihood of a successful VBAC. These include a previous vaginal delivery or a previous successful VBAC, a C-section scar that is horizontal and low on the abdomen, and the reason for the original C-section. If the original C-section was done for reasons that are unlikely to recur – such as a breech position – it bodes well for a successful VBAC. However, if the C-section was due to factors such as lack of progression of labour or a narrow pelvis, these may also affect subsequent pregnancies.
Dr. Akoury discussed some of the reasons why overall caesarean rates may be increasing.
‘Maternal age is a big contributor to caesarean section rates,’ he said, adding that the number of older mothers has been rising over the last 10 years. In women over 40, the C-section rate is almost 50 per cent, which is nearly twice the rate seen in younger women, Dr. Akoury said.
Other factors include the type of hospital. Teaching hospitals are thought to have lower C-section rates because they have greater resources to deal with different labour situations. Smaller hospitals may be unable to offer highly specialized care round-the-clock, so some more complicated births may end in C-section.
Other factors that may influence caesarean rates include maternal obesity, doctors who are wary of legal action, and maternal requests for caesarean. However, Dr. Akoury noted that maternal obesity is not increasing at the same rate as C-sections, and also added that maternal requests likely account for a very small percentage of caesareans.
Before weighing the risks and benefits of VBAC, Dr. Akoury discussed the risks and benefits of C-sections and vaginal births in general.
Although maternal mortality rates are very low, maternal deaths are three to six times more common in caesarean deliveries than vaginal births, Dr. Akoury said. There are somewhere between six and 20 maternal deaths for every 100,000 caesareans.
Deep vein thrombosis, interoperative bleeding and infection are other maternal risks associated with C-sections.
Risks to the baby include accidentally cutting the baby while performing the surgery, and a higher risk of certain breathing problems in newborns.
One of the more important risks associated with caesarean birth is the increased likelihood of placenta accreta (abnormal attachment of the placenta to the uterus) in future pregnancies. Placenta accreta is a serious obstetrical complication, and the risk increases with each subsequent C-section.
But vaginal delivery can also have risks. Operative vaginal deliveries – those that involve forceps or a vacuum – can have high complication rates, Dr. Akoury said.
‘If we’re going to be insistent on reducing caesarean section, vaginal delivery will go up and concurrently, operative vaginal delivery will go up,’ he said.
Vaginal delivery can result in pelvic floor dysfunction, such as incontinence. Risk is higher for first-time mothers, those with large babies and those who have a prolonged second stage of labour.
For women attempting VBAC, risks include uterine rupture or tearing of their C-section scar. Compared to a successful VBAC, a failed VBAC attempt triples these risks, and more than doubles the risk of hysterectomy.
Dr. Akoury notes that uterine rupture is rare, and affects a small number of women.
In terms of risks to the baby, fetal death during labour is more frequent in VBAC, and so is oxygen deprivation, which can cause damage to the brain and central nervous system. Once again, Dr. Akoury noted that these are rare occurrences. The rate of neonatal deaths is similar for VBAC and caesarean births.
‘To summarize, maternal morbidity is probably slightly higher in caesarean section than VBAC. Maternal mortality is (also) slightly higher with the elective section,’ Dr. Akoury said. ‘Perinatal mortality and severe complications occur more frequently, but in small numbers, with a VBAC.’
The overall caesarean rate continues to rise, which means more women will be making choices about attempting VBAC or having an elective C-section during a subsequent pregnancy. Information about the risks and benefits of both options will be critical for making these decisions.
