Tips from Other Journals

Primary Cesarean Delivery Increases Risks in Next Pregnancy

Am Fam Physician. 2007 Oct 15;76(8):1210-1214.

Background: Rising rates of cesarean births and an increasing number of patients, especially primiparous women, requesting cesarean delivery have stimulated interest in the delivery method's impact on subsequent pregnancies. Initial studies have reported an increase in unexplained stillbirths and other adverse outcomes after a previous cesarean delivery. These adverse effects cannot be attributed to the delivery method without adjusting for many factors, in particular the indication for the initial cesarean delivery. Kennare and colleagues analyzed differences in second pregnancy outcomes between women who had a previous cesarean delivery and those who had a previous vaginal delivery.

The Study: The large retrospective study included singleton second births to women in South Australia from 1998 to 2003. Data were abstracted from a validated, comprehensive, statewide pregnancy reporting system that included sociodemographic, pregnancy, birth, and neonatal information on all live and stillbirths that had a gestational age of at least 20 weeks or that had a birth weight of at least 14.1 oz (400 g). The statistical analyses adjusted for age, indigenous status, smoking status, pregnancy interval, medical conditions (i.e., hypertension, diabetes, or asthma), obstetric complications, patient insurance status (i.e., public or private), gestational age, and obstetric history (i.e., ectopic pregnancy, miscarriage, stillbirth, or termination).

Results: More women who had a previous cesarean delivery were 30 years or older and were privately insured patients compared with those who had a previous vaginal delivery. Conversely, fewer women in the previous cesarean delivery group were smokers or had pregnancy intervals less than 15 months.

Women who delivered their first child by cesarean had a significantly increased risk of adverse outcomes in their second pregnancy, including placenta previa, antepartum hemorrhage, malpresentation, prolonged labor, and cesarean delivery; the risk of emergency cesarean delivery increased the most (see accompanying table). Rare events such as uterine rupture and placenta accreta also were significantly more common in mothers who delivered their first child by cesarean. Two maternal deaths occurred in the previous cesarean delivery group (one from hemorrhage following hysterectomy for placenta accreta and one from amniotic fluid embolism following uterine rupture). There were no maternal deaths in the vaginal delivery group. Infants whose mothers had a previous cesarean delivery had increased risk of being small for gestational age, premature, or stillborn.

Risks of Adverse Outcomes in a Second Pregnancy After a Previous Cesarean Delivery

Outcomes in second pregnancy Previous delivery method Adjusted odds ratio (95% CI) P NNH
Cesarean (n = 8,725) Vaginal (n = 27,313)

Placenta previa

109 (1.25%)

187 (0.68%)

1.66 (1.30 to 2.11)

< .001

225

Placental abruption

66 (0.76%)

169 (0.62%)

1.22 (0.90 to 1.64)

NS

Antepartum hemorrhage

325 (3.72%)

846 (3.10%)

1.23 (1.08 to 1.41)

.002

146

Malpresentation

581 (6.69%)

960 (3.52%)

1.84 (1.65 to 2.06)

< .001

36

Prolonged labor

42 (1.11%)

50 (0.19%)

5.89 (3.91 to 8.89)

< .001

109

Cesarean delivery (emergency and elective)

6,721 (77.03%)

2,503 (9.16%)

8.54 (8.41 to 8.67)

< .001

3

Emergency cesarean delivery

2,117 (51.37%)

1,490 (5.67%)

9.37 (8.89 to 9.76)

< .001

3

Preterm birth

489 (5.60%)

1,271 (4.65%)

1.17 (1.04 to 1.31)

.009

134

Low birth weight

379 (4.34%)

949 (3.47%)

1.3 (1.14 to 1.48)

< .001

101

Stillbirth

43 (0.49%)

94 (0.34%)

1.56 (1.04 to 2.32)

.030

528


CI = confidence interval; NNH = number needed to harm; NS = not significant.

Adapted with permission from Kennare R, Tucker G, Heard A, Chan A. Risks of adverse outcomes in the next birth after a first cesarean delivery. Obstet Gynecol 2007;109:273.

Risks of Adverse Outcomes in a Second Pregnancy After a Previous Cesarean Delivery

View Table

Risks of Adverse Outcomes in a Second Pregnancy After a Previous Cesarean Delivery

Outcomes in second pregnancy Previous delivery method Adjusted odds ratio (95% CI) P NNH
Cesarean (n = 8,725) Vaginal (n = 27,313)

Placenta previa

109 (1.25%)

187 (0.68%)

1.66 (1.30 to 2.11)

< .001

225

Placental abruption

66 (0.76%)

169 (0.62%)

1.22 (0.90 to 1.64)

NS

Antepartum hemorrhage

325 (3.72%)

846 (3.10%)

1.23 (1.08 to 1.41)

.002

146

Malpresentation

581 (6.69%)

960 (3.52%)

1.84 (1.65 to 2.06)

< .001

36

Prolonged labor

42 (1.11%)

50 (0.19%)

5.89 (3.91 to 8.89)

< .001

109

Cesarean delivery (emergency and elective)

6,721 (77.03%)

2,503 (9.16%)

8.54 (8.41 to 8.67)

< .001

3

Emergency cesarean delivery

2,117 (51.37%)

1,490 (5.67%)

9.37 (8.89 to 9.76)

< .001

3

Preterm birth

489 (5.60%)

1,271 (4.65%)

1.17 (1.04 to 1.31)

.009

134

Low birth weight

379 (4.34%)

949 (3.47%)

1.3 (1.14 to 1.48)

< .001

101

Stillbirth

43 (0.49%)

94 (0.34%)

1.56 (1.04 to 2.32)

.030

528


CI = confidence interval; NNH = number needed to harm; NS = not significant.

Adapted with permission from Kennare R, Tucker G, Heard A, Chan A. Risks of adverse outcomes in the next birth after a first cesarean delivery. Obstet Gynecol 2007;109:273.

Conclusion: The authors conclude that a first cesarean delivery is associated with increased risk of adverse outcomes in a subsequent pregnancy. They believe these findings have serious implications for women who elect to have their first child via cesarean delivery.

Source

Kennare R, et al. Risks of adverse outcomes in the next birth after a first cesarean delivery. Obstet Gynecol. February 2007;109:270–6.


Copyright © 2007 by the American Academy of Family Physicians.
This content is owned by the AAFP. A person viewing it online may make one printout of the material and may use that printout only for his or her personal, non-commercial reference. This material may not otherwise be downloaded, copied, printed, stored, transmitted or reproduced in any medium, whether now known or later invented, except as authorized in writing by the AAFP. Contact afpserv@aafp.org for copyright questions and/or permission requests.

Want to use this article elsewhere? Get Permissions


Article Tools

  • Print page
  • Share this page
  • AFP CME Quiz

Information From Industry

Navigate this Article