Muscle Gain During Pregnancy: What To Expect

Can you BUILD muscle during pregnancy?

A lot of women (and trainers) have asked me if this is a reasonable goal during pregnancy. As always, the answer starts with “it depends” - MOSTLY it will depend on whether you are already trained or not.

So let’s first talk about women who are TRAINED - i.e. they already lift weight and have muscle mass.

(Scroll down to the next section to learn about UNtrained pregnant women, if you want to start lifting weights during your pregnancy, or if you are a trainer and want to know for a trainee)

In short, no, it isn't reasonable to expect to BUILD muscle during pregnancy. (Sorry, I know that’s not what you wanted to hear).

While it may theoretically be possible to MAINTAIN (and our goal should definitely be to maintain as much as we can) it is unlikely and one should expect to LOSE muscle mass and strength over the course of pregnancy.

This is due to physiological and anatomical changes; the hormonal milieu affects the elasticity of our connective tissue, so force production in the muscles decreases.

Think: if the connective tissue attaching the muscles to the bones are more elastic, the muscles have to work much harder to produce the same force.

Therefore, it isn't reasonable to expect to load the muscles as much as before pregnancy, and since mechanical load is one of the mechanisms of hypertrophy, it will affect our ability to gain muscle while pregnant.

The other two mechanisms of hypertrophy are muscle damage and metabolic stress, both of which will be harder to achieve under the hormonal (and anatomical) changes of pregnancy.

Anatomical changes will also affect your ability to produce force, especially in large, compound movements that allow you to mechanically load the muscles, like squats, deadlifts and pullups.

You’ll also want to consider your pelvic floor... and while you might be able to lift heavy loads, it probably isn’t ideal for your pelvic floor.

Some training guidelines specific to lifting weights that you should consider if you are pregnant:

1. You want to learn to EXHALE on the EFFORT. Many of you will be chronic breath holders, and if you lift heavy, you’ll be used to “bracing” - this isn’t recommended during pregnancy because the best information we have suggests that it puts a lot of pressure down on the pelvic floor and pelvic organs. Breath holding (and/or valsalva) can increase blood pressure and may have a negative effect on foetal heart rate.

2. So you’ll want to select weights that you can lift while EXHALING - this helps regulate intra-abdominal pressure and may help the pelvic floor support the pelvic organs.

3. You’ll also want to work to an RIR of 1-3 reps, so leave a couple of reps in the tank, rather than maxing out or reaching failure.

4. Some guidelines recommend lifting in a higher rep range of 8-15 reps, rather that 5 rep maxes or 1 rep maxes- although it may still be safe to lift for 5 reps if you leave a couple in the tank.