Eating for two?

It is a common misconception that once a woman is pregnant, she is “eating for two”.  This is a risky way to think, as in many cases it will lead to higher gestational weight gain than required or recommended. 

Recommended weight gain is based on a woman’s pre-pregnancy body mass index (BMI).  BMI is a measurement that takes into account a person’s height and weight through a simple calculation – weight (kg)/height (metres)². A normal BMI is between 18.5 and 24.9. To calculate your BMI, check out http://www.nhlbisupport.com/bmi/ or the chart below:

 

For a regular pregnancy with one baby, the Institute of Medicine (IOM) and Health Canada recommend a 12.5-18 kg (28-40 lb) weight gain if the pre-pregnancy BMI is underweight (<18.5). If the pre-pregnancy BMI is normal, a woman should gain between 11.5-16 kg (25-35 lbs). For a woman who starts off overweight (BMI 25-29.9) or obese (BMI >30), she should gain 7-11.5 kg  (15-25 lbs) and 5-9 kg (11-20 lbs), respectively.  

In order to achieve your recommended weight gain, most women only need to increase their caloric intake slightly (ie. you only require approximately 300 extra calories per day, which is roughly equivalent to a sandwich).

Gaining too much weight can lead to problems for both you and your baby during and after the pregnancy. Higher gestational weight gain may lead to gestational diabetes, gestational hypertension and a caesarean section delivery, to name just a few. You may be at higher risk of preterm delivery or your baby being large for gestational age.  Furthermore, after your delivery, the more weight you have gained, the longer it will take you to achieve your pre-pregnancy weight  On the flip side, not gaining enough weight can negatively affect fetal growth and also increase the risk of early delivery.

Keep in mind, these are general recommendations and don't guarantee that you will have a negative pregnancy outcome if you fall outside the guidelines. You should always check with your doctor on how much gestational weight gain is appropriate for you, to give you and your baby the optimal outcome.