# Presentation: 698248

## Body Mass Index and the First Born Baby: Effects on Conception and Reproduction

*Suzanne Tough*, PhD*
*Karen Tofflemire, MSc*
*December 8, 2005*

## Objectives

- Describe characteristics of women according to their pre-pregnancy BMI
- Asses the relationship between pre-pregnancy BMI and :
-    - pregnancy complications
-    - infant birth weight and preterm birth
- 3.  Describe weight gain during pregnancy based on IOM guidelines for BMI and assess the relationship between weight gain and infant birth weight.

## Methods

- Stratified random sample of  1002 women selected from Calgary and Edmonton, Alberta (urban centres)
- Women contacted within 8 months of giving birth to their _first_ child
- Computer Assisted Telephone Interview
- Statistical analysis included frequencies, bivariate analysis and multiple logistic regression

## Characteristics of Women according to their pre-pregnancy BMI

## Pre-pregnancy BMI

- <18.5:        Underweight
- 18.5-24.9:  Normal weight
- 25.0-29.9:  Overweight
- ≥30.0:        Obese

** Health Canada: Canadian Guidelines for Body Weight Classifications in Adults, 2003*

## Characteristics

- Obese women were more likely* to:
- Be older
- Have  lower education
- Diagnosed with depression and/or anxiety
- More likely to rate their physical health as poor

- * bivariate analysis, Chi-Square p, all < 0.05

## BMI and pregnancy complications

## Obesity and Pregnancy

-    Obese women were significantly* more likely (compared to women with normal BMI) to:
- Experience pre-eclampsia
-    OR* = 1.98, 95% CI: 1.09-3.61
- Experience gestational diabetes
-    OR* = 13.83, 95% CI: 2.50-76.55

- *Adjusted for age, education, income, ethnicity and history of depression

## BMI & Time to Pregnancy

- Months to become pregnant

*Significant difference between obese and normal, ANOVA, p<0.05, using the Scheffe method for multiple comparisons*

## Assisted Reproductive Technology and BMI 

**Assisted Reproductive Technology and BMI**** **

- IVF = in vitro fertilization
- ICSI = intracytoplasmic sperm injection

- Pre-pregnancy BMI

## Pre-pregnancy BMI and Infant Outcomes

## Pre-pregnancy BMI, LBW & preterm birth

**Pre-pregnancy BMI, LBW & preterm birth**

- P>0.05 for both

- Pre-pregnancy BMI

## Weight Gain during Pregnancy

## Weight Gain During Pregnancy

**71.8%** of the women gained between 6.8 and 18.2 kg*
*    ***recommended by the Society of Obstetricians and Gynaecologists of Canada (SOGC)*
**HOWEVER****, if pre-pregnancy BMI is used as a guideline for pregnancy weight gain (singleton pregnancies only N=983) overall, 21% of women gained less and 41 % gained more than recommended for their BMI.**

## Weight Gain during Pregnancy

| BMI  
(recommended 
weight gain)*  | Less | Recommended | More |
| --- | --- | --- | --- |
| <20    
(12.5-18.2 kg) | 27.3% | 50% | 22.7% |
| 20-27  
(11.5-16.0 kg) | 24.1% | 36.8% | 39.1% |
| >27     
(6.8-11.5 kg) | 9.5% | 30.7% | 59.8% |

**Health Canada: Nutrition for a Healthy Pregnancy – National Guidelines for the Childbearing Years; 2002*
* **and Nutrition During Pregnancy. Part I – Weight Gain. Washington, DC: National Academy Press; 1990.*

## Weight Gain based on pre-pregnancy BMI and Association with Infant Birth Weight

## LBW Infants and Weight Gain

## Macrosomic Infants & Weight Gain

## Infant Outcomes

- Overall,** 10.8%** of women who gained less weight than recommended for their BMI gave birth to a low birth weight infant (<2500 g) compared to **4.0%** of women who gained at least the weight recommended
*(Adjusted OR=2.96, 95% C.I. 1.64-5.35).*
- Overall,** 16.5%** of women who gained more than the recommended weight for their BMI had a macrosomic infant (>4000 g) compared to **6.0%** of women who gained within the recommended guidelines
*(Adjusted OR=3.48, 95% C.I. 2.18-5.55).*

## Summary

- A high body mass index had negative effects on reproduction and was associated with pregnancy complications
- Pregnancy weight gain outside recommendations for pre-pregnancy BMI had negative effects on infant birth weight

## Implications

- Weight loss programs should be encouraged for obese women with infertility problems
- Healthy weight gain should be encouraged for all women of childbearing age
- Particular attention should be given to pre pregnancy BMI and recommended weight gain during pregnancy

## Acknowledgements

- Corine Frick
- Christine Newburn-Cook
- Nonie Fraser-Lee
- Karen Benzies

- Ian Lange
- Reg Sauve
- Alexandra Faber

- Funding provided by:

## Thank-You!

- www.calgaryhealthregion.ca/dsrt/
- _[suzanne.tough@calgaryhealthregion.ca](mailto:suzanne.tough@calgaryhealthregion.ca)_