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When is the best time for C-section?

Deciding when to schedule a C-section is an important decision that requires careful consideration of multiple factors. The timing of a Cesarean delivery can impact the health and well-being of both mother and baby. This article provides an overview of the pros and cons of scheduling a C-section at different points during pregnancy so mothers can make an informed decision about what is right for them.

What is a C-section?

A Cesarean section, also known as a C-section, is a surgical procedure used to deliver a baby through incisions in the abdomen and uterus. It is usually done when a vaginal delivery would put the baby or mother at risk. C-sections can be planned ahead of time or done when an emergency occurs during labor.

Reasons for a Planned C-section

There are various reasons a doctor may recommend a planned C-section instead of waiting for labor to begin naturally. Some common reasons include:

  • The baby is in a breech or transverse position
  • The baby is too large for the birth canal (cephalopelvic disproportion)
  • The placenta is covering the cervix (placenta previa)
  • The mother has a health condition that makes vaginal delivery risky such as heart disease or diabetes
  • The mother is carrying multiples like twins or triplets
  • The mother has had a previous C-section or uterine surgery

In many cases, a planned C-section is scheduled for 39 weeks of pregnancy, but determining the optimal timing requires looking at the unique circumstances of each patient.

What are the Options for Timing a Planned C-section?

If a C-section is necessary, the timing of the surgery is an important decision. Doctors typically recommend scheduling a planned C-section at one of these points during pregnancy:

  • 34-37 weeks: Early term delivery between 34-37 weeks.
  • 37-38 weeks: Full term delivery between 37-38 weeks.
  • 39 weeks: The most common time for a planned C-section.
  • After 40 weeks: Post-term delivery after 40 weeks if labor has not started.
  • 41-42 weeks: Delivery typically recommended by 41-42 weeks to avoid risks of going past the due date.

The best timing is based on balancing the maturity of the baby’s lungs and other organs with the medical reason for the C-section. Let’s look at the advantages and disadvantages of each option.

C-section at 34-37 Weeks

Delivery between 34-37 weeks is considered early term. A C-section may be scheduled during this time if there are medical complications or conditions that make continuing the pregnancy dangerous for the mother or baby. Some examples include preeclampsia, placental abruption, or fetal growth problems.

Pros of 34-37 Weeks

  • Intervenes early if mother or baby is at risk
  • baby is at lower risk for stillbirth than waiting longer
  • Babies at 36-37 weeks do well with few complications

Cons of 34-37 Weeks

  • Increased risk of breathing problems at 34-35 weeks
  • Higher chance of low birth weight and nicu stay
  • Possible feeding issues or jaundice in early term babies

Babies delivered even a couple weeks early can have more complications, so risks and benefits must be weighed carefully.

C-section at 37-38 Weeks

Delivering at 37-38 weeks is considered full term. Babies born during this time are unlikely to have major health issues related to prematurity. This is a common and recommended time for a planned C-section if medical factors indicate it.

Pros of 37-38 weeks

  • Baby’s lungs and organs are mature
  • Low risk of breathing problems or nicu stay
  • Avoid risks of waiting too long if problems are suspected

Cons of 37-38 weeks

  • Slightly higher newborn jaundice risk
  • Potential feeding or blood sugar issues
  • Minimally higher risk of stillbirth than 39-40 weeks

In most cases, the benefits outweigh the small risks at this stage.

C-section at 39 Weeks

39 weeks is the most common timing for planned C-sections if there are no pressing medical issues. By 39 weeks, the risks of prematurity are very low but risks of prolonged pregnancy have not yet increased.

Pros of 39 weeks

  • Excellent lung maturity and organ development
  • Lower risks than delivery before 39 weeks
  • Avoids potential problems of going late

Cons of 39 weeks

  • Slightly higher stillbirth risk than 37-38 weeks

For most low-risk pregnancies, 39 weeks is ideal in balancing risks and benefits.

C-section after 40 Weeks

If a woman’s pregnancy continues past her due date and labor does not start naturally, a C-section may be recommended. This is to avoid potential problems with post-term pregnancy.

Pros of after 40 weeks

  • Allows pregnancy to progress naturally as long as possible
  • Maximizes maturity if baby is not showing signs of distress

Cons of after 40 weeks

  • Risk of placental deterioration increases
  • Higher likelihood of macrosomia and shoulder dystocia
  • Small increase in stillbirth risk

The risks of waiting often outweigh the benefits beyond the due date, leading to a recommendation for scheduled delivery.

C-section at 41-42 Weeks

Many doctors recommend delivery by 41-42 weeks at the latest if labor does not start naturally. The placenta has a hard limit on functioning, so risks increase after this point.

Pros of 41-42 weeks

  • Maximizes time for spontaneous labor

Cons of 41-42 weeks

  • Higher stillbirth rates and risk of distress
  • Greatly increased risk of placental insufficiency
  • Much higher risk of complications like macrosomia
  • Requires intense fetal monitoring

Due to increased risks and monitoring needs, most providers will recommend delivery by 41-42 weeks at the latest.

Factors in Determining Optimal Timing

Along with the risks at each stage listed above, there are several important factors that impact figuring out the best timing for an individual patient.

Why the C-section is Needed

The medical reason for the surgery influences recommended timing. If it is an absolute emergency like heavy bleeding, delivery needs to happen as soon as safely possible. If the reason is a mild condition or previous C-section, there is more flexibility.

Fetal Development

Lung maturity and overall fetal growth should be considered. Testing lung function can help determine if there are benefits to waiting.

Chorionicity in Multiples

In twins or triplets, whether babies share a placenta impacts timing. Earlier delivery is often needed with identical twins sharing a placenta.

Risk Factors and Complications

Issues like preeclampsia, diabetes, or placental abnormalities affect scheduling. Doctors balance the risks and benefits closely.

Stillbirth Statistics

Historical patterns of stillbirth rates may influence the provider’s recommendations for balancing risks.

How is the Due Date Determined?

Knowing the due date accurately based on the first day of the woman’s last menstrual period or ultrasound dating impacts scheduling decisions. Uncertainty about the due date can affect the choice of timing.

Here is a table summarizing the pros and cons of each C-section timing option:

Timing Pros Cons
34-37 weeks Intervenes early if problems occur
Lower risk of stillbirth than waiting longer
36-37 weeks reasonable for maturity
Increased breathing issues at 34-35 weeks
Higher NICU and feeding risks
Babies are still early term
37-38 weeks Mature lungs and organs
Low NICU and breathing risks
Avoids prolonged pregnancy risks
Slightly higher jaundice
Potential blood sugar/feeding issues
Minimally higher stillbirth risk
39 weeks Excellent maturity
Lower risks than earlier delivery
Avoids problems of waiting longer
Slightly higher stillbirth rates than 37-38 weeks
After 40 weeks Allows most time for natural labor
Maximizes maturity if no issues seen
Increased placental risks
Higher macrosomia and stillbirth risks
41-42 weeks Maximum time for spontaneous labor Much higher stillbirth risk
Greatly increased placental risks
More macrosomia and distress


Deciding on the ideal timing for a C-section is a complex decision that requires balancing multiple risks and benefits. Most experts recommend delivering between 37-39 weeks for uncomplicated planned C-sections. However, each patient’s unique health factors must be taken into account. Going into early term or post-term has increasing risks, so those choices should be made carefully. Discussing all considerations with your obstetrician is important for determining the best time to meet your baby if you plan a Cesarean delivery.