Canadian Gestational Weight Gain Recommendations

This content was archived on June 24, 2013.

Health Canada has adopted the 2009 U.S. Institute of Medicine (IOM) recommendations for gestational weight gain for singleton pregnancies. The IOM recommendations are based on observational data, which consistently show that women who gain within the recommended range experience better pregnancy outcomes.

Gestational weight gain recommendations are based on a woman's pre-pregnancy body mass index (BMI). Entering pregnancy with a normal BMI and gaining within the recommended gestational weight gain ranges minimizes maternal, fetal and newborn risks. This does not mean, however, that every woman who exceeds or falls short of the recommended weight gain will have an unhealthy pregnancy. Many other factors besides maternal weight and gestational weight gain (such as smoking and maternal age) may affect pregnancy outcomes.

Recommended rate of weight gain and total weight gain for singleton pregnancies according to pre-pregnancy BMI (adapted from Institute of Medicine, 2009)

Pre-pregnancy BMI category	MeanTable 1 footnote a rate of weight gain in the 2nd and 3rd trimester		RecommendedTable 1 footnote b range of total weight gain
	kg/week	lb/week	kg	lbs
Table 1 footnotes Table 1 footnote a Rounded values. Return to table 1 footnote a referrer Table 1 footnote b Calculations assume a total of 0.5 - 2 kg (1.1 - 4.4 lbs) weight gain in the first trimester. Return to table 1 footnote b referrer Table 1 footnote c A narrower range of weight gain may be advised for women with a pre-pregnancy BMI of 35 or greater. Individualized advice is recommended for these women. Return to table 1 footnote c referrer
BMI < 18.5 Underweight	0.5	1.0	12.5 - 18	28 - 40
BMI 18.5 - 24.9 Normal weight	0.4	1.0	11.5 - 16	25 - 35
BMI 25.0 - 29.9 Overweight	0.3	0.6	7 - 11.5	15 - 25
BMI ≥ 30Table 1 footnote c Obese	0.2	0.5	5 - 9	11 - 20

Questions and Answers on the Canadian Gestational Weight Gain Recommendations

1. What are the risks associated with gaining too much or too little weight during pregnancy?
2. What advice can be given to a woman who has gained beyond the recommended weight gain for her stage of pregnancy?
3. How much total weight gain is recommended for women carrying multiple fetuses?
4. What are the differences between Health Canada's previous gestational weight gain recommendations and the 2009 Institute of Medicine recommendations?
5. What process was used by Health Canada to adopt the U.S. Institute of Medicine recommended weight gain guidelines?
6. What is Health Canada doing to help women meet the recommendations for weight gain during pregnancy?
7. How can I learn more about the process the Institute of Medicine used to develop their recommendations?

1. What are the risks associated with gaining too much or too little weight during pregnancy?

The adverse outcomes of excess weight gain during pregnancy for mothers include increased risk of Caesarean sections or retaining extra weight after delivery. In turn, post-partum weight retention can lead to obesity. For the child, the risks include being born pre-term or larger than normal. Gaining too little weight during pregnancy can also negatively affect fetal growth and increase the risk of pre-term delivery.

2. What advice can be given to a woman who has gained beyond the recommended weight gain for her stage of pregnancy?

Weight loss is not recommended during pregnancy. Women who have already surpassed the recommended weight gain should be encouraged to continue gaining weight at an appropriate rate of gain based on their pre-pregnancy BMI. These women will need additional support in the post-partum period to lose the extra weight gained during pregnancy.

3. How much total weight gain is recommended for women carrying multiple fetuses?

The 2009 Institute of Medicine (IOM) report titled Weight Gain During Pregnancy: Reexamining the Guidelines provides provisional guidelines for women carrying twins:

• normal weight women should gain between 17 and 25 kg (37-54 lbs),
• overweight women, between 14 and 23 kg (31-50 lbs) and
• obese women, between 11 and 19 kg (25 - 42 lbs) at term.

Based on the IOM review of evidence, there is insufficient information available to develop guidelines for underweight women carrying twins and for women carrying more than two fetuses.

4. What are the differences between Health Canada's previous gestational weight gain recommendations and the 2009 IOM recommendations?

The new IOM recommendations are not dramatically different from those published previously by Health Canada. The recommendations do, however, differ in three ways:

1. the IOM recommendations are aligned with the World Health Organization's (WHO) definitions of underweight (BMI less than 18.5), normal weight (BMI of 18.5 to 24.9), overweight (BMI of 25.0 to 29.9) and obese (BMI of 30 or greater);
2. they include a suggested rate of weight gain in addition to recommendations for total gain during pregnancy; and
3. they have a specific recommendation for a lower amount of total weight gain for obese women.

5. What process was used by Health Canada to adopt the U.S. Institute of Medicine recommended weight gain guidelines?

Before adopting the U.S. Institute of Medicine 2009 recommendations for weight gain during pregnancy, Health Canada and the Expert Advisory GNational Nutrition Pregnancy Guidelines considered the evidence base for the IOM recommendations as well as findings from the  2006-07 Maternity Experiences Survey (MES).

A summary of each of the following documents was reviewed and considered as part of this process:

• Influence of Pregnancy Weight on Maternal and Child Health (2006 IOM Workshop Report)
• Outcomes of Maternal Weight Gain (2008 Systematic Review prepared for the Agency for Healthcare Research and Quality, AHRQ Publication No. 08-E009)
• Weight Gain during Pregnancy: Adherence to Health Canada's Guidelines (analysis of data from the 2006-07 Canadian Maternity Experiences Survey, publication pending)
• Weight Gain During Pregnancy: Reexamining the Guidelines (2009 IOM Pre-publication Report)

Current available evidence supports the use of the IOM recommendations in the Canadian context; however, an important issue will be their implementation, as many Canadian women are gaining outside of the recommended weight gain ranges. (See What is Health Canada doing to help women meet the recommendations for weight gain during pregnancy?)

6. What is Health Canada doing to help women meet the recommendations for weight gain during pregnancy?

To help support the implementation of the IOM recommendations, Health Canada is developing tools and resources for health care providers and pregnant women that will help them track total gain and rate of weight gain during pregnancy. Messages will focus on being physically active and eating well before, during and after each pregnancy.

7. How can I learn more about the process the IOM used to develop their recommendations?

The 2009 IOM report titled Weight Gain During Pregnancy: Reexamining the Guidelines provides background on the recommendations for gestational weight gain. The IOM report can be accessed on the  National Academies Press Web site.