Strength training when pregnant - is it safe?

Does this picture make you take a sharp intake of breath?

As with anything pregnancy related there are thousands of opinions and contradictory statements on what women should do. Strength training however has some pretty clear guidelines, so why do pictures like this of Lea-Ann Ellison still cause an outcry?

When Lea-Ann's picture went viral some of the comments were "this is a good way to lose your baby" with others describing the picture as "sickening". There is NO scientific basis for these sorts of comments what so ever. It makes me angry to read such stories as women already face negative stigmas when strength training and with the Institute of Medicine highlighting pregnancy as a critical risk for inactivity and obesity this is not helpful in encouraging women to stay active during pregnancy. In fact 60% of pregnant women remain sedentary for the whole term. Whilst some women may want to or have to rest the whole time, those who choose to maintain an active lifestyle should not be judged and shamed in this way.

Let me go through some of the science for you by starting with some highlights:

  • Physically active pregnant women have 59% less chance of developing gestational diabetes compared to inactive women

  • Exercise during pregnancy can prevent preeclampsia

  • Body image anxiety and rates of depression are lower in pregnant women who exercise

  • Women who were performing vigorous exercise during pregnancy went on to have 5 year olds who were more neurodevelopmentally advanced and attentive

The original statement from the American College of Obstetrics and Gynaecologists (1995) that started to build negative opinions on pregnant women strength training, was based on animal studies and conservative opinion. They have since revised their stance in 2002 to say that exercise is safe and they recommend 30mins or more of moderate exercise 2-6 per week. So were the concerns unfounded in the first place? Absolutely not, of course anything that could put a women's pregnancy at risk should be avoided. The main theories behind exercise causing problems were related to hyperthermia, spontaneous abortion and damage to joints.

So let's explore each part:

Hyperthermia (overheating)

Once again this stemmed from animal studies where they were pushing the species to the point of exhaustion which is not what would pregnant women would practice. The worries being that exercise can raise a women's core temperature which can damage the foetus particularly in the early stages. This is why exercising in the heat is generally considered a bad idea. Studies in humans have found no impact of maternal exercise on foetal development however one of the recommendations from this is to keep exercise at a sub maximal intensity, with the 'talk test' often used to gauge effort.

This is where the possibility for shock at pictures such as Lea-Ann's comes in. This may look like an incredibly hard exercise to a lot of people but in Lea-Ann's case this is probably way under her maximum effort. So the beauty of this recommendation is that it's relative. So where dead lifting might push some people over their conversational zone, others can continue with 60+KG without breaking much sweat.

Spontaneous abortion

Miscarrying due to exercise seems to have had no evidence behind it to start this concern aside from the hyperthermia argument described above. The only contraindications with exercise that could cause spontaneous abortion are related to direct trauma to the stomach i.e. contact sports, martial arts, road cycling, horse riding. Strength training has either been shown to have no effect on the risk of miscarriage or in some studies there was a lower incidence in women who were strength training.

Joint Damage

It is well known that from 12 weeks onwards the hormone relaxin is released making all joints more lax in preparation for the baby growing and labour process. This can cause more pain particularly in the lower back and pelvis. However research does not show an increase in exercise related injuries during pregnancy. In fact there has been some evidence that strength training during pregnancy can prevent these pains developing. If I see a pregnant women with this type of pain in clinic, I would certainly be prescribing strength work to increase the stability at the pelvis and lower back which is something that should be continued after the baby is born to ensure the stability returns once relaxin is out of the system.

As mentioned in the introduction the guidelines for strength training in pregnancy are clear, so whilst there are some concerns and in some cases contraindications to exercise there shouldn't be any question that strength training and exercise in general is a good thing to continue with during pregnancy. So what are the guidelines? Let's start with the no no's according to the Canadian Guidelines for Exercise in Pregnancy.

If you have any of these things you should not be exercising whilst pregnant :

  • Significant heart disease

  • restrictive lung disease

  • multiple babies - at risk of premature labour

  • persistent vaginal bleeding

  • placenta previa after 26 weeks

  • ruptured membranes

  • preeclampsia/pregnancy induced hypertension

  • premature labour during current pregnancy

The next list are things that might be a contraindication to pregnancy and as above should be checked with your doctor before starting training:

  • Severe anaemia

  • Cardiac arrhythmia

  • Poorly controlled type 1 diabetes

  • Morbid obesity

  • Chronic bronchitis

  • Extremely underweight (BMI <12)

  • Poorly controlled high blood pressure

  • Poorly controlled seizure disorder

  • Poorly controlled hyperthyroidism

  • History of extreme sedentary lifestyle

The last point is important, as there are separate guidelines for people starting an exercise programme when pregnant. A golden rule and generally accepted principle is that you are aiming to MAINTAIN exercise levels not exceed them or start new things whilst pregnant. The statement from the ACOG is that maternal exercise is safe when carried out by healthy women within their current abilities. This brings us back to the point that this is relative to your current level of activity. Pregnancy is not the time to PB despite perhaps wanting to take advantage of the extra human growth hormone circulating!

So here are some of the do's and don'ts of exercising when pregnant:


  • Do some exercise! Both aerobic and strength training can have multiple benefits for you and your baby

  • Keep the intensity below maximum level - use the talk test/70% as a rough guide

  • Listen to your body - you will be the best judge of when something doesn't feel right

  • Breathe! Holding your breath can be damaging as described below so aim to breathe out when doing the hard parts to avoid this


  • Exercise in the heat

  • Do ballistic movements in the later stages - this puts unnecessary strain on the pelvis and pelvic floor muscles that will already be under a lot of load

  • Start new exercise - stick to what you are comfortable with this is not the time to experiment

  • Do contact sports or exercise that could mean you fall/take direct trauma to the abdomen

  • Do the valsalva manoeuvre - holding your breath whilst performing a strength exercise has it's place but not when pregnant. It increases the heart rate and blood pressure which can decrease blood flow to the foetus

  • Exercise on your back after the 2nd trimester (16 weeks) - this can block the vena cava (biggest vein in the body)

  • Pay attention to shocked/negative looks in the gym - the general public is not as well informed as you so sadly this will still happen

The warning signs to watch out for when exercising are:

  • Vaginal bleeding

  • Dizziness

  • Headache

  • Chest pain

  • Calf pain or swelling

  • Decreased foetal movement

  • Amniotic fluid leaking

As with anything pregnancy related, if you are concerned then check with your midwife/doctor to make sure in your specific case exercise is not contra-indicated.

In my opinion strength training is a key part of staying healthy during pregnancy and preparing for labour. A commonly overlooked area for pregnant women are arms! If you've ever held a baby they can feel pretty heavy pretty quickly and they only get bigger and more unpredictable so having the upper body strength to cope with this is a good starting point. I hope this article has shed some light on the myths around exercise and pregnancy and whilst we may not all be lifting as heavy as Lea-Ann, pregnancy is no reason to put the weights down.


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#pregnancy #strength #weights #guidelines