Understanding the associations between operative vaginal delivery and obstetric trauma and birth trauma

Q&A with lead author, Dr. Giulia Muraca.

Our group has been working for the last six years to compare mom and baby outcomes in deliveries for which an uncomplicated vaginal delivery is no longer an option and intervention by forceps, vacuum, or cesarean delivery is required. These analyses included data from hundreds of thousands of deliveries across the country.

 What were the objectives of this study?

In this study, we wanted to get a better understanding of the associations between operative vaginal delivery and obstetric trauma and birth trauma. Obstetric trauma – injuries to the mother – included injuries such as severe tearing of the perineum, vagina or cervix and injury to the bladder or pelvis. Severe birth trauma – or injury to the baby – included complications such as permanent nerve palsies, fracture of the long bones, and brain damage.

We first measured how often these traumas occurred in Canada and then we assessed how the rates of these traumas have changed over time. Lastly, we examined the relationship between these rates of trauma and the rates of different modes of delivery, such as forceps delivery or vacuum delivery.

 Why was it important to do this study among operative vaginal deliveries in Canada?

In Canada, cesarean delivery rates have increased while the rates of forceps and vacuum (aka operative vaginal) deliveries have declined over the last few decades. This has led to recommendations to increase operative vaginal delivery rates as a strategy to reduce cesarean delivery rates.

The risks associated with cesarean delivery, such as infection or hemorrhage, and uterine rupture or morbid placentation in subsequent pregnancies, have been well characterized. However, high rates of obstetric trauma among women who had operative vaginal delivery has been overlooked. In our studies we found rates of obstetric trauma as high as 25% among women following forceps deliveries. Forceps and vacuum deliveries are carried out in approximately 10-13% of all term births in Canada; this translates to over 35,000 deliveries per year where women have endured obstetric injury.

What are the most important findings of the study?

We found that the rate of obstetric trauma in Canada increased significantly in recent years, especially among forceps deliveries. In first-time mothers, the rate of obstetric trauma increased from 19.4% in 2004 to 26.5% in 2014 and in women who had a previous cesarean delivery, the rate of obstetric trauma among forceps deliveries increased from 16.6% to 25.6%.  We found that a 1% increase in the operative vaginal delivery rate in Canada was associated with approximately 700 additional cases of obstetric trauma and 18 additional cases of severe birth trauma annually among first-time mothers alone.

 Our results suggest that encouraging higher rates of forceps and vacuum delivery as a strategy to reduce the cesarean delivery rate could result in substantial increases in obstetric trauma and severe birth trauma.

How may these findings potentially affect patient care?

We found that 86% of the cases of obstetric trauma among operative vaginal deliveries in our study were due to severe perineal lacerations. This type of injury is linked to future pelvic floor health – such as anal incontinence and pelvic organ prolapse, one of the most common indications for gynaecologic surgery.

Women need to be informed about the substantially increased risk of severe obstetric injury following all forceps and vacuum deliveries along with the relevant long-term quality-of-life implications.

Are any strengths or limitations in this study especially worth noting?

The nature of our large, population-based study allowed us to characterize trauma trends and to stratify these trends by mode of delivery as well as by parity and obstetric history. We did not have information on all the variables we would have liked to have included in our analyses, such as pre-pregnancy BMI in mothers, and operator skill. Also, we did not have information on long-term outcomes, such as placental abnormalities in subsequent pregnancies among women who had a cesarean delivery, or rates of incontinence in the years following delivery.

Should we abandon deliveries by forceps and vacuum?

No, we are not advocating for the abandonment of forceps and vacuum delivery. These are valuable interventions that provide alternatives for women who require interventions during labour. There are certain circumstances during labour, when the fetus is showing signs of distress for example, when a swift delivery with forceps or vacuum can make the difference in a child’s life and long-term health. Forceps and vacuum deliveries carried out by highly skilled obstetricians have saved the lives of countless babies over the last several decades.

However, improvements in surgery and anesthesia, and changes in the number of children women are having in countries such as Canada appear to have altered the relative safety profile of cesarean delivery versus forceps and vacuum delivery.

Our results should make policy-makers cautious about recommending increased operative vaginal delivery rate without evaluating the maternal and perinatal outcomes associated with this reduction.

The bottom line is that each of these modes of delivery carry their own sets of benefits and risks.

Rather than focusing narrowly on rates of caesarean section we should focus on indices of perinatal and maternal severe morbidity and mortality that quantify safety and well-being of mothers and babies. And this is what should be communicated to women for consideration when they are formulating a birth plan.

What further related research are you planning?

Further research is required to shed light on the reasons for the high rates of obstetric trauma in Canada among operative vaginal deliveries, the implications for affected women and the healthcare system, both acute and long-term, and the burden attributable to operative vaginal delivery.

Want to learn more – read the full CMAJ article – and check out the media coverage.