1. Birth by the Numbers Gene Declercq March, 2016
Is there a relationship between pre-pregnancy obesity and cesarean section
Birth by the Numbers
Gene Declercq
March, 2016

2. Long Standing Concern with Maternal Obesity

3. Contemporary Categorization of Obesity
BirthByTheNumbers.org

4. BMI & Obesity Categories
Category
Person 5’4”
<18.5
Underweight
< 110 lbs
18.5 – 24.9
Normal Weight
25.0 – 29.9
Overweight
30.0 – 34.9
Obese I
35.0 – 39.9
Obese II
40+
Obese III
235+
BirthByTheNumbers.org

5. Trends in U.S. Obesity over Time

6. Obesity Trends* Among U.S. Adults BRFSS, 1985
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14%

7. Obesity Trends* Among U.S. Adults BRFSS, 1986
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14%

8. Obesity Trends* Among U.S. Adults BRFSS, 1987
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14%

9. Obesity Trends* Among U.S. Adults BRFSS, 1988
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14%

10. Obesity Trends* Among U.S. Adults BRFSS, 1989
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14%

11. Obesity Trends* Among U.S. Adults BRFSS, 1990
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14%

12. Obesity Trends* Among U.S. Adults BRFSS, 1991
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19%

13. Obesity Trends* Among U.S. Adults BRFSS, 1992
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19%

14. Obesity Trends* Among U.S. Adults BRFSS, 1993
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19%

15. Obesity Trends* Among U.S. Adults BRFSS, 1994
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19%

16. Obesity Trends* Among U.S. Adults BRFSS, 1995
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19%

17. Obesity Trends* Among U.S. Adults BRFSS, 1996
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19%

18. Obesity Trends* Among U.S. Adults BRFSS, 1997
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19% ≥20%

19. Obesity Trends* Among U.S. Adults BRFSS, 1998
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19% ≥20%

20. Obesity Trends* Among U.S. Adults BRFSS, 1999
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19% ≥20%

21. Obesity Trends* Among U.S. Adults BRFSS, 2000
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19% ≥20%

22. Obesity Trends* Among U.S. Adults BRFSS, 2001
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19% %–24% ≥25%

23. Obesity Trends* Among U.S. Adults BRFSS, 2002
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19% %–24% ≥25%

24. Obesity Trends* Among U.S. Adults BRFSS, 2003
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19% %–24% ≥25%

25. Obesity Trends* Among U.S. Adults BRFSS, 2004
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19% %–24% ≥25%

26. Obesity Trends* Among U.S. Adults BRFSS, 2005
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19% %–24% %–29% ≥30%

27. Obesity Trends* Among U.S. Adults BRFSS, 2006
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19% %–24% %–29% ≥30%

28. Obesity Trends* Among U.S. Adults BRFSS, 2007
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19% %–24% %–29% ≥30%

29. Obesity Trends* Among U.S. Adults BRFSS, 2008
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19% %–24% %–29% ≥30%

30. Obesity Trends* Among U.S. Adults BRFSS, 2009
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
No Data <10% %–14% %–19% %–24% %–29% ≥30%

31. Obesity Trends* Among U.S. Adults BRFSS, 2010
(*BMI ≥30, or ~ 30 lbs. overweight for 5’ 4” person)
Why do maps stop in 2010?
No Data <10% %–14% %–19% %–24% %–29% ≥30%

32. Trends in Obesity, US Adult Women, 1988-2012
Source: NHANES surveys
BirthByTheNumbers.org

33. Prepregnancy Obesity, U.S. (sort of)* 2003, 2006, 2009, 2011*, 2013*
While there is justifiable concern with the health consequences of obesity overall and in pregnancy, maternal prepregnancy obesity has also levelled off in recent years.
Sources: S. Fisher. Is obesity still increasing among pregnant women?
Preventive Medicine 2013; 56: ; 2011 & 2013 – CDC VitalStats.
* Based on different combinations of states in 2011 & 2013
BirthByTheNumbers.org

34. Term, Singleton, Vertex (TSV) , No prior Cesarean
Term – 37 + weeks gestation
Singleton – no twins
Vertex – no breech births
No prior cesarean
BirthByTheNumbers.org

35. BMI categories for Term, Singleton, Vertex births to mothers w/ no prior cesarean: 38 states & DC, 2012
Characteristic of mother
Under-weight
Normal weight
Overweight and obese
Total
Over-weight
Total Obese
Obese I
Obese II
Obese III
(BMI<18.5)
(BMI )
(BMI 25+)
(BMI )
(BMI 30+)
(BMI )
(BMI )
(BMI ≥40.0)
(N=88,638)
(N=
1,066,630)
1,002,074)
(N=542,296)
(N=459,778)
(N=266,872)
(N=118,111)
(N=74,795)
All
4.1
49.4
46.4
25.1
21.3
12.4
5.5
3.5
Race and Hispanic origin
Hispanic
3.1
44.4
52.5
29.1
23.4
14.7
5.6
3.0
Non-Hispanic
White
4.0
52.3
43.7
23.9
19.8
11.3
5.2
3.3
Black
3.7
38.7
57.6
27.1
30.5
16.1
8.0
6.3
AIAN
37.1
59.8
27.3
32.5
17.7
9.1
5.7
Asian
9.5
66.9
23.5
17.5
6.1
4.7
1.0
0.3
BirthByTheNumbers.org

36. Prepregnancy Obesity also related to:
Being born in the U.S. (23%) rather than foreign born (15%)
Being on private insurance (25%) rather than Medicaid (19%)
Having only a high school education (25%) compared to a graduate degree (12%)
BirthByTheNumbers.org

37. Also related to how many kids you’ve had: Obesity by Live Birth Order, 2013
BirthByTheNumbers.org

38. How is BMI related to the likelihood of a cesarean?
BirthByTheNumbers.org

39. Unadjusted Primary Cesarean Rate TSV births to mothers with no prior cesarean: 38 states and DC, 2012
Cesarean rates vary dramatically by obesity categories.
Source: CDC VitalStats, 2013.
BirthByTheNumbers.org

40. CS Rates for TSV mothers by BMI and Race/Ethnicity
BirthByTheNumbers.org

41. Overall relationship adjusted for:
maternal age,
race/ethnicity,
education,
trimester prenatal care began,
nativity (US or foreign-born),
method of payment for the delivery,
pre-pregnancy and gestational diabetes and hypertension.
BirthByTheNumbers.org

42. Adjusted~ risk ratios^ for CS by BMI, TSV
Adjusted~ risk ratios^ for CS by BMI, TSV* Mothers w/ no Prior CS, 38 states, 2012
~ Adjusted for maternal age, race/ethnicity, education, trimester prenatal care began, nativity (US or foreign-born), method of payment for the delivery, and pre-pregnancy and gestational diabetes and hypertension.
^ “Normal weight” (BMI ) was the reference group; Error Bars represent 95% Confidence Intervals.
*Singleton, vertex, weeks of gestational age. LBO = live birth order
BirthByTheNumbers.org

43. Conclusion
BMI retains a significant impact on the likelihood of a CS, even after controlling for socio-demographic and medical risks
Robust relationship that was consistent across different analyses of subgroups (e.g. mothers without diabetes or hypertension)
What about outcomes? Future Birth by the Numbers video
BirthByTheNumbers.org

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