Tienchin Ho

Elective Repeat Cesarean Sections

A New England Journal of Medicine article this month discusses outcomes for babies born by elective repeat cesarean section. Here is a link to a New York Times article about the study.

In this study, data on 19 university hospitals was taken from the Eunice Kennedy Shriver National Institute of Child Health and Human Development cesarean registry. The investigators looked at 28,867 patients with prior cesarean sections who had repeat cesarean sections. Patients who had cesareans before 37 weeks were excluded from the study. Those who were in labor or already had spontaneous rupture of membranes were also excluded.

Then, for each case, the investigators determined the reasons for the cesarean section. Only cesareans without a medical reason were considered elective.

Some of the reasons they found were:
multiple gestations
non vertex presentation
major malformations
maternal medical problems such as heart disease or HIV
prior uternie incision that was not low transverse
non-reassuring fetal heart tracing or fetal testing
suspected macrosomia (abnormally large baby)
placenta previa or abruption

There were 13,258 elective repeat cesarean sections done after 36 weeks (46% of all repeat cesarean sections).

Distribution of elective repeat cesarean sections by gestational age:
37 weeks          834 pts     6.3% of all elective cesareans
38 weeks        3909         29.5%
39 weeks        6512         49.1%
40 weeks        1385         10.4%
41 weeks          505           3.8%
>= 42 weeks     113           0.9%

Then the investigators tracked the babies' outcomes.

They looked for:
death
breathing problems
hypoglycemia
severe newborn infection
seizures
hypoxis ischemic encephalopathy
CPR
signs of severe stress
admission to the neonatal ICU
hospitalization for 5 days or more

They found that babies born by elective repeat cesarean section before 39 weeks were at higher risk for having these problems.

babies born at:
37 weeks    15.3% had problems       had 2.1 times the risk of problems compared to 39 weeks
38                11.0%                                1.5
39                 8.0%                                 ----     
40                 7.3%                                 0.9
41               11.3%                                 1.4
>=42           19.5%                                 2.5

The researchers concluded from their study two things.

First, that elective repeat cesarean sections before 39 weeks is common (one-third of all repeat elective cesarean sections).

Second, earlier cesareans have an increased risk of neonatal complications.

So, what does all this mean to a pregnant woman trying to make decisions?
If there are no medical problems, this study suggests that she can minimize the risk of problems with baby by scheduling the cesarean section after reaching 39 weeks.

In real life, however, there are two situations I can think of that make it difficult to apply this study. First, if a woman really wants an elective repeat cesarean section, how does she know she isn't going to go into labor before 39 weeks? There would be pressure to have a cesarean section sooner rather than later to make sure she was really going to get an elective repeat cesarean section. This is the sort of decision that may seem easy for those of us who are not pregnant but can be excruciating for women who are.

Second, this study was based on trained reviewers looking at medical records. Unrecorded conversations between providers and patients may include soft indications. For example, if I tell a mother that baby feels big, I haven't officially diagnosed macrosomia on the record, but I implied it to the mother. This may be the final straw for a woman to decide on an early repeat cesarean. In this study, her case would still be considered an elective repeat cesarean section. The woman, however, may feel her cesarean is medically indicated. She may feel it is better to have the cesarean earlier than 39 weeks to avoid having a big baby. This study suggests that by doing this, the baby will be at increased risk for complications. Given the known inaccuracies of predicting birth weight, I think using the possibility of a big baby as a medical indication for cesarean section before 39 weeks is problematic but more common than suggested by this study.

Dystocia and Quality Improvement

Dystocia or failure to progress refers to labors that are either progressing more slowly than expected or not progressing at all. The diagnosis of dystocia is responsible for half of all first-time (primary) cesareans in the United States.

The diagnosis and treatment of dystocia vary from doctor to doctor. For example, most obstetricians agree that cesarean section for dystocia is generally not recommended before the active phase of labor. Despite this, research shows that 15-20% of cesareans done for dystocia were done during latent phase instead. To standardize when a labor should be treated for dystocia, the American College of Obstetricians and Gynecologists (ACOG) published guidelines. As many as 35% of cesareans done for dystocia do not adhere to the published guidelines.

Of course, there are legitimate reasons in specific cases for not following a practice guideline. The ideal compliance rate is unknown. However, if we are trying to lower the 33% cesarean rate in the United States, this may be a place to start. Eliminating cesareans done outside of the guidelines could possibly reduce the 33% cesarean rate to under 25%.

Many birth professionals believe that differences in cesarean birth rates are a result of both patient and physician characteristics.

Dr. Eliott Main, chairman of the department of obstetrics and gynecology of California Pacific Medical Center (CPMC), demonstrates how a quality improvement program can change physician behavior in a way that published guidelines can not. In the program, each physician's cesarean rates and patient specifics are available to all physicians. His reason for this was to dispel the notion that a particular physician's patients are "more complicated than average." By showing that they all had similarly complicated patients and similarly good outcomes but varying cesarean rates, Dr. Main was able to convince physicians to critically examine their own practice patterns. Since implementing the feedback system in 1989, cesarean birth rates have dropped by 25% and have remained so.

In California the average cesarean section rate is 29%. At CPMC it is 19%. In Fresno it ranges from 24.5% to 34.5%.

Shoulder Dystocia

Shoulder dystocia is a term used to describe difficulty in birthing the shoulders of the baby after the head has emerged. Shoulder dystocia concerns families and caregivers because of its association with nerve injuries or death of the baby and bleeding or lacerations of the mother.

Bigger Babies
Women with exceptionally bigger babies (macrosomia) have a higher risk of experiencing shoulder dystocia. A study done in California (Nesbitt, 1998) reported the percentages of spontaneous births of nondiabetics complicated by shoulder dystocia for different birth weights.

Birth weight (lbs)	8.8 – 9.4	9.4 – 9.9	9.9 - 10.5	10.5 - 11
% of births complicated by shoulder dystocia	5.2%	9.1%	14.3%	21.1%

There is no guarantee that mothers with babies smaller than 8.8 lbs won't have shoulder dystocia. One study (Acker, 1986) found that nearly half of all shoulder dystocia cases occur during births of babies smaller than 8.8 lbs.

Given the correlation with birth weight, caregivers and families often try to predict birth weight in the hope of preventing shoulder dystocia and its complications.

Predicting Baby's Size
Predicting fetal weight by ultrasound or clinical palpation (Leopold’s maneuvers) is imprecise. Our expectation that ultrasound would be more accurate at predicting birth weight than clinical estimates has not been confirmed. One study (Chauhan, 1992) found that a mother's own estimate of birth weight was more likely to be within 10% of the actual birth weight than either a physician's clinical estimate or an ultrasonographic estimate.

Method of estimation	Mother’s estimate	Clinical estimate	Ultrasound estimate
% of estimates within 10% of the actual birth weight	70%	66%	42%

Other Risk Factors
In addition, women with diabetes are also at higher risk for encountering shoulder dystocia during their labor. This risk factor is independent of birth weight (Dildy, 2000).

Most researchers also report an association between shoulder dystocia and operative vaginal delivery (forceps or vacuum extraction). Operative vaginal delivery is also associated with an increased risk of nerve injuries (Belfort, 2007).

What Should We Do?
Despite our current inability to accurately determine baby’s birth weight until after the birth, some caregivers use their best guess and recommend intervention.

Some providers tout early induction as a method to birth a baby before it gets “too big.” Other providers advocate cesarean section for suspected macrosomia as a method to avoid shoulder dystocia. Because these approaches have not been shown to improve outcomes for mother or baby, the American College of Obstetricians and Gynecologists does not recommend induction or cesarean section for all women with suspected macrosomia (ACOG practice bulletin #40).

For non-diabetic women with babies estimated to be over 11 lbs or for diabetic women with babies estimated to be over 9.9 lbs, scheduled cesarean section has not been shown to improve outcomes for either mother or baby. This may be in part due to a trade-off of other risks to mother and baby that increase with cesarean sections. In addition, most cases of shoulder dystocia can be successfully managed without additional injury to baby or mother. ACOG states that scheduled cesarean section may be considered in these cases.

One researcher (Rouse, 1996) calculated that over 1000 cesarean sections would have to be performed in non-diabetic women with suspected macrosomia in order to prevent one nerve injury. In addition, such a policy would have no effect on the almost equally prevalent cases of shoulder dystocia happening with babies that are smaller than 8.8 lbs.

Size Matters

The mother's size, the baby's size, even pelvic size and head size are common themes during pregnancy and childbirth. Here is a discussion about some familiar quotes.

“I shouldn’t gain too much weight during pregnancy.”

Our culture cultivates a fear of gaining weight. Body image concerns make the normal changes that occur during pregnancy scary. It is healthy and necessary to gain weight during pregnancy. Gaining weight during pregnancy does not equal getting fat. Although mothers weigh in at every prenatal visit, the quality of her diet, not her weight, determines the health of the pregnancy. Babies born too small are at risk for being premature, not being head-down, having umbilical cord prolapse, breathing problems, low blood sugar, and low body temperature.

“If I gain too much weight, my baby will be too big.”

Dietary restriction during pregnancy can impair fetal growth. Dietary supplementation with high protein, special amino acids, and other nutrients has not been proven to prevent impaired fetal growth. Fear of a big baby stems from the belief that this can lead to baby getting “stuck” during childbirth, cephalopelvic disproportion (CPD) or shoulder dystocia. Fortunately, these are not common and having a baby over 9 lbs does not condemn a mother to either one. Additionally, minimizing pregnancy weight gain does not prevent CPD or shoulder dystocia.

“My ultrasound shows that my baby is going to be too big for me to birth vaginally.”

Ultrasounds done late in pregnancy are not accurate in predicting birth weight, but do increase the rate of early hospital admissions and inductions without any benefit to baby.

“Special x-rays and pelvimetry can determine whether my pelvis is big enough to pass a baby.”

Neither x-ray nor clinical pelvimetry predict the adequacy of a woman’s pelvis during childbirth. Labor is the only reliable test.

“My baby is getting too big so I need to be induced.” Or “My baby is getting too big so I need to have a cesarean section.”

Inducing labor in women thought to have a “big” baby does not produce healthier babies or mothers. It does increase the likelihood of other interventions and cesarean sections. Planned cesarean section for women thought to have “big” babies does not produce healthier babies or mothers.

“If I don’t lose weight within the first 3 months after childbirth, I’ll be fat.”

In order to remodel her body and establish her milk supply, a woman should avoid intentional weight loss until at least three months postpartum. A growing infant needs calories, vitamins, protein and fats to grow healthy. Breast milk provides all of these best, and even in cases of severe calorie restriction breast milk maintains its nutrition for baby. A mother should ensure her diet is adequate to maintain her own health. Although mothers who breastfeed seem to lose more weight on average than those who do not, sometimes the weight loss happens after breastfeeding stops.

“So what should I eat?”

A healthy diet is healthy before, during and after pregnancy.

Resources:

• FDA report on mercury levels in fish
• Eat, Drink, and Be Healthy by Walter Willett - Harvard professor in nutrition and epidemiology involved in NHANES studies (National Health and Nutrition Examination Survey)
• La Leche League - guidelines for diet and weight management with breastfeeding

Avoid:
Trans fats
High fructose corn syrup
High-mercury containing fish
    (king mackerel, shark, swordfish, tilefish)

Minimize:
Chips                French fries
Soft drinks        Candy
Alcohol             Caffeine

Include:
Protein: eggs, dairy, meats, fish, nuts, nut butters
Essential oils: fish, nuts, nut butters and oils, olive oil
Salt to taste
B12 500mcg a day
folate 500mcg a day

No limit on:
Whole fruit (not canned, frozen ok)
Whole vegetables (not canned, frozen ok)
Whole grains
Beans
Nuts
Red raspberry leaf tea