Consequences of Gestational Weight Gain:

Outcomes for the mother and child Ellen Aagaard Nohr June 5, 2008 IOM workshop on GWG Guidelines

Danish National Birth Cohort

Aim of this talk! Presentation of our study : “Combined associations of

prepregnancy BMI and gestational weight gain on the outcome of pregnancy” by Nohr EA, Vaeth M, Baker J, Sorensen T, Olsen J, Rasmussen KM. Will be published in this months issue of American Journal of Clinical Nutrition. June 5 2008

IOM workshop on GWG Guidelines

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Danish National Birth Cohort

Aim of the study: To investigate the combined associations of prepregnancy BMI and gestational weight gain with pregnancy outcomes.

To evaluate the trade-offs between mother and infant for different weight gains.

June 5 2008

IOM workshop on GWG Guidelines

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The Danish National Birth Cohort - in short DNBC !!

Danish National Birth Cohort

Still the world’s largest cohort in a pregnant population. 100,000 women and their offspring (1997-2002) Ethnicity ? Caucasian women ! • Only 3.5% of the cohort is not of Scandinavian origin. Prevalence of obesity ? Behind the US, but on the rise !

June 5 2008

IOM workshop on GWG Guidelines

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Antenatal care in Denmark during the study period

Danish National Birth Cohort

Stable, universal and tax paid health care system where more than 99% of women access public prenatal care. GWG recommendations The official Danish Guideline stressed not to be concerned about weight gain. Lack of evidence. ‘No reason for control of weight at every visit!’ Midwives’ reaction: Most continued weighing and documenting weight at every visit. However, not much weight gain advice was given. June 5 2008

IOM workshop on GWG Guidelines

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Data collection in the DNBC

Danish National Birth Cohort

Birth First interview

Second interview

Third interview

Pregnancy

First visit 16 weeks at family doctor

June 5 2008

Infancy

30 weeks

• Blood samples: Women/newborns

Fourth interview

½ year

1½ year

Pregnancy outcomes: • National Discharge Register • The Birth Register

IOM workshop on GWG Guidelines

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Danish National Birth Cohort

Data for study of GWG Second interview

First interview

Pregnancy

First 16 weeks Completed visit at GP by 92%

30 weeks

Third interview

Fourth interview

Infancy

½ year Completed by 70%

1½ year

Inclusion criteria: • Pregnanies ending with term liveborn singletons. • Participation in first and third interview. • Information about ’weight variables’.

Study population: 60,892 pregnancies June 5 2008

IOM workshop on GWG Guidelines

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Material & methods

Danish National Birth Cohort

Self-reported anthropometric variables: Main exposures: Categorised prepregnancy BMI (WHO): • • • •

Underweight: Normal weight: Overweight: Obese:

20 kg

Gestational weight gain

IOM workshop on GWG Guidelines

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Danish National Birth Cohort

Post partum weight change at 6 months 10.00

10.00

Post partum retention ≥ 5 kg Post partum loss ≥ 2 kg

6.2 3.2

2.8

2.3

Odds Ratio

1.9 1.3

1.0

1.00

1.1 1.00

0.5

0.4

0.4 0.3

Under weight

Normal weight

Over weight

0.10

Prepregnancy BMI

Obese

< 10 kg

10 - 15 kg

16 - 19 kg

> 20 kg

0.10

Gestational weight gain

Post partum weight retention was strongly associated with weight gain Chance of post partum weight loss was equally strongly related to BMI and weight gain. June 5 2008

IOM workshop on GWG Guidelines

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Danish National Birth Cohort

Post partum weight change at 6 months 10.00

10.00

Post partum retention ≥ 5 kg Post partum loss ≥ 2 kg

6.2 3.2

2.8

2.3

Odds Ratio

1.9 1.3

1.0

1.00

1.1 1.00

0.5

0.4

0.4 0.3

Under weight

Normal weight

Over weight

0.10

Prepregnancy BMI

Obese

< 10 kg

10 - 15 kg

16 - 19 kg

> 20 kg

0.10

Gestational weight gain

Striking symmetry for the findings related to gestational weight gain June 5 2008

IOM workshop on GWG Guidelines

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Danish National Birth Cohort

Neonatal outcomes 10.00

10.00

Small-for-gestational-age Large-for-gestational-age

Odds Ratio

2.9 1.9

2.6

1.7

1.8

1.00

1.6

1.00

0.7 0.5

0.5

Under weight 0.10

0.7

0.7

Normal weight

Over weight

0.5

Obese

< 10 kg

10 - 15 kg

16 - 19 kg

> 20 kg

0.10

One increases while the other decreases in a beautiful symmetric pattern. June 5 2008

IOM workshop on GWG Guidelines

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Conclusions: Multiplicative models

Danish National Birth Cohort

Prepregnancy BMI was the strongest predictor of the outcomes under study. The contribution of gestational weight gain was modest except for birth weight and post partum weight. Only little interaction between BMI and GWG: Present for birthweight and post partum weight retention • June 5 2008

Judged to be of little clinical importance… IOM workshop on GWG Guidelines

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RESULTS 2 AN ADDITIVE APPROACH:

Comparison of absolute risk differences across BMI groups IOM workshop on GWG Guidelines

Absolute risk: Small-for-gestational-age infant 0.6

Underweight

0.5

0.5

0.4

0.4

↓ 37%

0.3

Adjusted absolute risk

0.6

0.2

0.1

0.1

0.0 Low

Medium

0.6

High

0.0 Very high

Overweight

0.5

0.4

0.4

↓ 9%

Low

0.2

0.1

0.1

0.0

Medium

High

SGA below 10%

0.3

0.2

Especially underweight women should avoid lower gains !

↓ 16%

0.6

0.5

0.3

Normal weight

0.3

0.2

Danish National Birth Cohort

Very high

Obese

↓ 5%

0.0 Low

Medium

High

Very high

Low

Medium

High

Very high

Total weight gain category June 5 2008

Points present risks of a primiparous woman, aged 25-29, height 160-69, non-smoker, workshop onexercise GWGand Guidelines no alcohol consumption,IOM high social status, no 280 days of gestation.

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Absolute risks: Large-for-gestational-age infant and emergency caesarean delivery 0.6

Underweight

0.5

0.5

0.4

0.4

↑~5%

0.3

Adjusted absolute risk

0.6

0.2

0.1

0.1

0.0 Low

Medium

0.6

High

0.0 Very high

Overweight

0.5

0.4

0.4

↑ ~ 6-11 %

0.2

0.1

0.1

0.0

0.0 Very high

Low

Medium

High

Low

Medium

High

Very high

Obese

LGA above 90% Emergency CS

↑ ~ 11–13 %

0.3

0.2

Risk differences increase with increasing BMI !

↑ ~ 6- 7 %

0.6

0.5

0.3

Normal weight

0.3

0.2

Danish National Birth Cohort

Low

Medium

High

Very high

Total weight gain category June 5 2008

Points present risks of a primiparous woman, aged 25-29, height 160-69, non-smoker, workshop onexercise GWGand Guidelines no alcohol consumption,IOM high social status, no 280 days of gestation.

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Absolute risks: Post partum weight retention ≥ 5kg 6 months post partum 0.6

Underweight

0.5

0.5

0.4

0.4

↑ ~ 40 %

0.3

Adjusted absolute risk

0.6

0.2

0.1

0.1

0.0 Medium

0.6

High

0.0 Very high

Overweight

0.5

0.4

0.4

↑ ~ 40 %

0.2

0.1

0.1

0.0

0.0 Medium

Same risk increase with higher gains. Low

Medium

High

PPWR at 6 months

Very high

Obese

Very different clinical relevance…

↑ ~ 40 %

0.3

0.2

Low

↑ ~ 40 %

0.6

0.5

0.3

Normal weight

0.3

0.2

Low

Danish National Birth Cohort

High

Very high

Low

Medium

High

Very high

Total weight gain category June 5 2008

Points present risks of a primiparous woman, aged 25-29, height 160-69, non-smoker, workshop onexercise GWGand Guidelines no alcohol consumption,IOM high social status, no 280 days of gestation.

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Absolute risks: 4 important pregnancy outcomes 0.6

Underweight

Normal weight

0.5

0.5

≥20 kg

0.3

0.3

0.2

0.2

0.1

0.1

0.0

0.0 Very high

Low

Medium

0.6

High

Overweight

0.5

Medium

Low

0.6

0.4

0.4

0.3

0.3 20 kg. Obese women may benefit from low gain < 10 kg.

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IOM workshop on GWG Guidelines

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RESULTS 3: Migration in BMI groups according to GWG

IOM workshop on GWG Guidelines

Danish National Birth Cohort

BMI-migration in underweight women according to GWG 6 months post partum 100%

Prepregnancy BMI

90% 80%

obese 2+3

70%

obese 1

60%

overweight normal weight

50%

underweight

40% 30% 20% 10% 0%

Under weight June 5 2008