Medical Minute: Weight Gain in Pregnancy

As I type this – I fully own the fact that I myself have never carried a child.  I have never had to struggle with hormones, weight gain, or the responsibility of anything more than nourishing myself or my cat.

With that being said – I feel confident in my level of practice with women who are pregnant – I typically work with more women who are in high risk pregnancies- women who have put on too much weight in a short period of time, or not enough weight, and or women who are at risk to have gestational diabetes, women who have gestational diabetes, and women who have diabetes prior to conception.

With being pregnant the amount of weight gained is extremely important – too little can be problematic, as can too much gain.

While there is no “one size fits all” recommendation- I use the standards below when recommending weight gain in pregnancy- which are all based on pre-pregnancy weight, and BMI.  These are standards backed by Mayo Clinic and IOM to name a few.

Pre-pregnancy weight Recommended weight gain
Underweight (BMI < 18.5) 28 to 40 lbs. (about 13 to 18 kg)
Normal weight (BMI 18.5 to 24.9) 25 to 35 lbs. (about 11 to 16 kg)
Overweight (BMI 25 to 29.9) 15 to 25 lbs. (about 7 to 11 kg)
Obese (BMI 30 or more) 11 to 20 lbs. (about 5 to 9 kg

And these are the recs for anyone with multiple gestation

Pre-pregnancy weight Recommended weight gain
Normal weight (BMI 18.5 to 24.9) 37 to 54 lbs. (about 17 to 25 kg)
Overweight (BMI 25 to 29.9) 31 to 50 lbs. (about 14 to 23 kg)
Obese (BMI 30 or more) 25 to 42 lbs. (about 11 to 19 kg)

While BMI is not the end all be-all in terms of prediciting risk – it is a helpful tool in recommending weight gain for pregnant women.

So.  At 40 weeks this should be the composition of weight gain- for a woman who was of normal weight, who gained 32 lbs, and had an 8 lb infant:

Fetus > 8 lbs (23% of weight gained)

Placenta > ~ 1.5 lbs

Uterus > ~ 2.5 lbs

Amniotic Fluid > ~ 2 lbs

Breasts > 1 lb

Blood supply > ~ 3 lbs

Extracellular fluid > 7 lbs

Maternal fat stores > ~ 8 lbs


So this right here is basically where the weight gain during pregnancy is supposed to go.  Again that is not to say that someone who gains 35 or 25 lbs did anything more or less right or wrong.

Now in an individual who has a more unhealthy weight prior to conception will have greater fat stores to begin with – therefore addition fat stores do not need to be acquired.

So , with gaining too much weight- what can actually go wrong?

Hypertension (all forms), gestational diabetes/diabetes- as well as many other conditions are all related to inflammation, and oxidative stress, and damage to the endothelium (the layer of cells lining the inside of blood vessels).

Excessive weight gain is linked to issues linked to about everything in the hypertension family (gestational, preeclampsia, etc), gestational diabetes, etc.

To be fair inadequate weight gain has these same risks as well.

Aren’t I just a ray of sunshine today?!

Also there is a growing body of evidence that women in pregnancy- is a key time to examine when we look at adult obesity and well as childhood and adolescent obesity- and even when we observe catch up growth (very fast growth- many times can be mistaken as a growth spurt). Children who have catch up growth younger – typically have mom’s that did not have adequate weight gain.

Many current studies regarding childhood and adolescent obesity- have been integral in showing that there is a relationship and impact between the fetal environment, and a baby’s health outcomes.

An examination of risks

In pregnancy- it’s important to remember risk. So can you gain 70 lbs and still have a healthy baby? Yep. Is that something that can be a risk factor for bigger issues both in mom and baby, and both during pregnancy, and later in life? Yep.

Same goes for having a glass of vino, sushi, or tuna, or a steak medium rare. It’s a matter of risks.

(Women are more likely to be impacted by food borne illness is pregnancy – and it’s likely to affect them significantly greater than a non- pregnant woman.)

Just like everything else in life & health- pregnancy is a matter of risk.  Many women prefer to keep risks as minimal as feasibly possible.  But also many women do not recognize risks- whether they are nutrition related risks, weight related risks, health related risks etc.

A healthy pregnancy…in scientific terms

We can never know the outcomes of our endeavors.  However, as I have said before, and I will say again – if we are able to identify our risks – both modifiable and un-modifiable – that can really improve outcomes as a whole.


A very good place to start with a healthy pregnancy is, planning – and being in a reasonably good place nutritionally, health-wise etc at the time of conception. Especially as folic acid is most important in the first 6-8 weeks of pregnancy – a window that, unfortunately many women miss.

Keep up the activity.  Many women are active prior to pregnancy are able to continue with that level of activity into the pregnancy – maybe at reduced intensity, but unless you are given explicit instruction NOT to exercise- it’s typically cool

plate method

Nutrition: ok,  Sorry to be a huge buzzkill, but unless you’re pregnant with multiples – your caloric needs do not even increase until the second trimester.  And your caloric needs never really double- you’re NEVER eating for two.

In terms of a healthy diet – remember that plate I like to rave about? Follow that.  Get lot’s of colorful veggies, and some fruits, nice lean proteins, whole grains and complex carbs.


Make sure you are limiting your risks for foodborne illnesses too – so limit intake of deli meats, and pre-prepped salads (potato, macaroni), make sure your products are pasteurized, meats, seafood, and poultry should be fully cooked – as should eggs.

So to review:

Gaining too much or too little weight in pregnancy – can be harmful to both mom and baby.

Nutrition is really important – so focus on balance, and don’t be in the mind set of eating for two.  I’m not going to into the issue of organic/gmo/conventional – that is an entirely different animal- however again – a game of risk.

Physical activity is also really important – so continue with it during pregnancy – at a reduced intensity if need be.

Planning is key – ideally these pieces or many of them are in place, as is your healthy being stable prior to conception.

What works for some will not work for all, and while I’m not here to mom-shame anyone who gained an immense amount of weight, or not enough- my primary goal is to spread information.   As many individuals I work with – still abide by the thought of “eating for two”- not because they are gluttons, but because they truly do not know.  Just as many do not know – not gaining enough weight can be harmful as well.

With all of this being said – dietitians are a huge asset to a healthy pregnancy (obviously as a part of a larger healthcare team) . Whether it’s helping slow weight gain, or speed it up, and aiding in helping achieve blood sugar control when needed. So yes I can only imagine the stress and anxiety that can come from being pregnant – however I add this in closing. Please use sound and tried scientific recommendations and studies to guide you, and your choices- over that of mommy-blogs and talk shows. 


  1. I gained 25 lbs with my first child, and a good 40 with my second child. It’s so hard to stop the cravings when you are pregnant, LOL! Thankfully I was able to lose the weight fairly quickly.

  2. I’m currently at 10 lbs gained and 40 weeks on Saturday. Starting a pregnancy as obese it was super important to make sure I watched what I ate. Sure I had a love for chocolate frosties…. but it was a once a week thing. I was lucky to have a healthy pregnancy so far and need to lose some more weight before any additional ones.

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