Hunter Bennett

Exercising during pregnancy can have very positive outcomes for mother and baby alike. But did you know that pre-pregnancy exercise can also have an impact? Both influence weight gain during pregnancy.

Average And Recommended Weight Gain During Pregnancy

Weight gain during pregnancy is a completely normal thing. In fact, gaining some weight during pregnancy has been shown to positively affect both fetal and maternal health during the pregnancy period, immediately into the postpartum period, and even well into the future (Phelan, 2010).

However, both insufficient and excessive weight gain during pregnancy has been associated with numerous negative health outcomes. This has resulted in pregnancy weight gain guidelines being produced(Rasmussen, 2010).

The Guidelines:

•  Women who are underweight before pregnancy (BMI of less than 18.5) should gain between 27 and 40 pounds (or 12.5 and 18 kilograms) during pregnancy.
• Those who are of normal weight before pregnancy (BMI of between 18.5 and 24.9) should gain between 25 and 35 pounds (or 11.5 and 16 kilograms) during pregnancy.
• Women who are overweight before pregnancy (BMI of between 25 and 29.9) should gain between 15 and 25 pounds (or 7 and 11.5 kilograms) during pregnancy.
• Those who are obese before pregnancy (BMI greater than 30) should gain between 11 and 19 pounds (or 5 and 9 kilograms) during pregnancy.
• However, it is important to note that current research suggests that more than 70% of pregnant women gain more than the recommended weight during pregnancy, while around 10% gain less than recommended (Johnson, 2013).

If we were to break this down a little further, often those at most risk of gaining too much weight appear to be those who fall within the overweight and obese BMI categories before becoming pregnant.

Alternatively, those at risk of gaining too little weight tend to fall within the underweight category pre-pregnancy (Phelan, 2010).
Ultimately, this all means that only around 20% of all pregnant women gain within the recommended amount of gestational weight, leaving 80% of all pregnant women at risk of potential health complications.

Related Article: The Effect of Swimming During Pregnancy on Fetal Growth

How does weight gain differ during pregnancy between athlete, moderate exercisers, and physically inactive mothers?

There has been some recent research delving into the above in a little more detail, looking at how pre-pregnancy activity levels interact with gestational weight gain – and the results have been extremely interesting (Hegaard, 2017).

First and foremost, competitive athletes are the most likely to present within the underweight BMI category pre-pregnancy.

Similarly, those expecting mothers who perform moderate amounts of exercise were the most likely to fall within the normal BMI category, while women who performed no activity before becoming pregnant were the most likely to present as overweight or obese in accordance to their BMI. Even despite their typically underweight BMI status, elite athletes have been shown to gain the most amount of weight during pregnancy, in which they are much more likely to exceed the recommended guidelines.

Interestingly, both inactive and moderately active women appear to gain similar amounts, although a number of these individuals still gained more than currently recommended.
This suggests that competitive and elite athlete mothers are unlikely to make the necessary changes to diet that should occur in conjunction with their declining activity levels – essentially causing them to overeat during pregnancy, which drives up gestational weight gain.

What is the average birth weight of babies?

So, we have touched on how pre-pregnancy exercise levels can impact gestational weight gain, but how does it impact the birth weight of the baby?
But before we get into that, I first wanted to touch on the average baby birth weight.

Recommended healthy birth weights in newborn infants sit between 5.5 and 8.5 pounds (which is still a range that most newborn children fit into). With that in mind, a low birth weight is anything less than 5.5 pounds, while a high birth weight is anything more than 8.8 pounds.

Interestingly, over the last few decades, we have seen an increase in the number of children with what would be considered a high birth weight – and it may be the result of both pre-pregnancy BMI and gestational weight gain (Lima, 2018).

Does birth weight differ between athlete, moderate exercisers, and physically inactive mothers?

As one would expect, those mothers who start their pregnancy with a higher BMI traditionally see higher birth weights in their children. Moreover, those individuals who experience higher than normal weight gain during pregnancy also tend to experience higher infant birth weights (Lima, 2018).
But how do pre-exercise activity levels fit into this?

Quite interestingly, outside of these two factors, pre-exercise activity levels do not appear to have any influence on birth weight at all – even in competitive athletes who tend to experience much greater weight gain during pregnancy when compared to other individuals (Hegaard, 2017).

This is likely because even despite their heightened rate of weight gain, athletic individuals tend to exercise more during pregnancy than other mothers – and given that gestational exercise has been shown to positively influence birth weight, it is likely to mitigate the expected weight gain effect.

What is the average weight loss postpartum (and is there a recommended amount)?

While weight gain is indeed normal during pregnancy, we also know that weight gain across the lifespan is associated with an increased risk of disease and illness, as well as cancer, and declines in functional capacity.

As a result, there is reason to believe that prioritizing weight loss and returning to a healthy weight range after pregnancy is extremely important.
While there is no clear ‘average’ weight loss for women after pregnancy, recommendations sit within current guidelines – with the intent to return to (or in some cases, achieve) a healthy weight range within one year after pregnancy.

Taking this into consideration, on average most mothers tend to retain from 1 to 5 pounds of their gestational weight gain indefinitely after childbirth (Gunderson, 2009).
However, it is still important to note that around 20% of women will retain more than 10 pounds of their gestational weight gain after giving birth. A number of these individual move into overweight and obese health categories.

This truly indicates that more time needs to be invested in maximizing post-natal weight loss as a means to ensure the health of the mother.

How does post-pregnancy weight loss differ between athlete, moderate exercisers, and physically inactive mothers?

As you can imagine, this gestational weight retention again differs between athletic, moderately active, and inactive populations. In fact, 12 months after giving birth, competitive athletes are often the most likely to retain weight. Their average weight retention sits at around 5 pounds. This is most likely due to this group experiencing the most amount of weight gain during their pregnancy period (Vesco, 2016).

Alternatively, sedentary women tend to retain around 2 pounds of their gestational weight gain 12 months after pregnancy. Moderate exercisers will retain on average a mere 1.3 pounds within this timeframe.

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What percentage of mothers get back to their pre-pregnancy weight, and do pre-pregnancy activity levels make a difference?

Around 30% of all mothers tend to return their pre-pregnancy weight within 12 months of giving birth (Phelan, 2014).
Those individuals who were moderately active before becoming pregnant and can return to their pre-pregnancy exercise levels after giving birth are going to be more likely to return to their baseline weight (Hegaard, 2017).

It is also important to note that as weight gain during pregnancy appears to be the biggest predictor of weight retention after pregnancy, managing pregnancy weight gain through exercise is of serious importance.

What are the physical and emotional benefits of exercise during pregnancy?

Firstly, partaking in exercise throughout pregnancy will reduce the risk of excessive gestational weight gain and weight retention (Barakat, 2009).
Research shows physical exercise during pregnancy will increase the likelihood that the child will be born within a normal and healthy weight range. It will also reduce the risk of complications occurring during birth (Haakstad, 2011).

Secondly, it has demonstrated improved gestational cardiovascular and metabolic health. This reduces the risk of developing both gestational diabetes and preeclampsia (Roberts, 2003; Sklempe, 2018).

Finally, there are also mental benefits of exercise during pregnancy. Particularly, improving mood and energy levels while reducing the risk of developing post-natal depression in a very big way (Demissie, 2011).

Related Article: The Effect of Exercise on Postpartum Depression

What are the physical and emotional benefits of exercise postpartum?

Much like exercising during pregnancy, exercise after giving birth can also have a myriad of positive effects on the mother.
Exercise has been shown to mitigate the weight retention that many women experience after giving birth (Dewey, 1994). This can have a positive carryover effect on both cardiovascular and metabolic health (Lovelady, 1995).

Similarly, after giving birth you see declines in core muscle strength, which can contribute to lower back pain. Yet, by starting postnatal exercise, you can return function to those muscles while also making them stronger. Exercise post-pregnancy will also reduce your likelihood of developing low back pain (Mordved, 1996).

And finally, exercise after childbirth has been shown to cause large improvements in mood, energy levels, and depressive symptoms. All of this will has also been shown to increase feelings of value and self-worth (Poyatos‐León, 2017).

This results in huge improvements in mental health, in conjunction with a significantly reduced risk of developing postnatal depression. The benefits of exercise post pregnancy – and just as importantly, the mental benefits of exercise post pregnancy – are extremely potent.

Are there risks of returning to exercise too early?

Now, there are some risks associated with returning to exercise too soon after giving birth (Hinman, 2015).
Your ligaments tend to slacken during pregnancy to accommodate the large physical changes that your body undergoes. This means you are more susceptible to joint injuries. Additionally, your trunk and pelvic floor muscles are going to be in a weakened state after giving birth.

Your ability to stabilize your spine is going to be somewhat limited. This could result in the onset of a lower back injury.
These risks can be reduced by avoiding high impact activities for the first 4-6 weeks after giving birth. This means any exercise that involves explosive jumping, bounding, and sprinting is probably not your best bet.

During the first six weeks, your time might be better spent progressing into some moderate-intensity aerobic activity. These can be combined with some lower level abdominal and glute strengthening exercises.

Take Home Message

Your physical activity levels before becoming pregnant can seriously influence your weight gain during pregnancy. Especially regarding gestational weight gain and retention.
However, more important is your ability to maintain a healthy exercise regime both during and after the pregnancy period.

This will help to ensure your child is born within a healthy weight range. It will also mitigate any excessive weight gain and retention resulting from the pregnancy itself. Combine this with the huge mental and physical health benefits associated with exercise during this time period. You have yourself a winner!

References

Phelan, Suzanne. “Pregnancy: a “teachable moment” for weight control and obesity prevention.” American journal of obstetrics and gynecology 202.2 (2010): 135-e1.
Rasmussen, Kathleen M., et al. “Recommendations for weight gain during pregnancy in the context of the obesity epidemic.” Obstetrics and gynecology 116.5 (2010): 1191.
Johnson, Julie, et al. “Pregnancy outcomes with weight gain above or below the 2009 Institute of Medicine guidelines.” Obstetrics and gynecology 121.5 (2013): 969.
Hegaard, Hanne Kristine, et al. “Influence of pre-pregnancy leisure time physical activity on gestational and postpartum weight gain and birth weight–a cohort study. ” Journal of Obstetrics and Gynaecology 37.6 (2017): 736-741.

Lima, Raina Jansen Cutrim Propp, et al. “Prepregnancy body mass index, gestational weight gain, and birth weight in the BRISA cohort. ” Revista de saude publica 52 (2018): 46.
Gunderson, Erica P. “Childbearing and obesity in women: weight before, during, and after pregnancy.” Obstetrics and Gynecology Clinics 36.2 (2009): 317-332.
Vesco, Kimberly K., et al. “One‐year postpartum outcomes following a weight management intervention in pregnant women with obesity.” Obesity 24.10 (2016): 2042-2049.

Phelan, Suzanne, et al. “Does behavioral intervention in pregnancy reduce postpartum weight retention? Twelve-month outcomes of the Fit for Delivery randomized trial–.” The American journal of clinical nutrition 99.2 (2013): 302-311.
Barakat, Rubén, A. Lucia, and Jonatan R. Ruiz. “Resistance exercise training during pregnancy and newborn’s birth size: a randomized controlled trial.” International journal of obesity 33.9 (2009): 1048.

More References

Haakstad, Lene AH, and Kari Bø. “Exercise in pregnant women and birth weight: a randomized controlled trial.” BMC pregnancy and childbirth 11.1 (2011): 66.
Sklempe Kokic, Iva, et al. “Acute responses to structured aerobic and resistance exercise in women with gestational diabetes mellitus.” Scandinavian journal of medicine & science in sports (2018).

Roberts, James M., et al. “Summary of the NHLBI working group on research on hypertension during pregnancy.” Hypertension in Pregnancy 22.2 (2003): 109-127.
Demissie, Zewditu, et al. “Associations between physical activity and postpartum depressive symptoms.” Journal of Women’s Health 20.7 (2011): 1025-1034.
Dewey, Kathryn G., et al. “A randomized study of the effects of aerobic exercise by lactating women on breast-milk volume and composition. ” New England Journal of Medicine 330.7 (1994): 449-453.

Lovelady, Cheryl A., et al. “Effects of exercise on plasma lipids and metabolism of lactating women.”.  Medicine and science in sports and exercise 27.1 (1995): 22-28.
Mordved, Siv, and Kari Bo. “The effect of post‐natal exercises to strengthen the pelvic floor muscles.” Acta obstetricia et gynecologica Scandinavica 75.4 (1996): 382-385.
Poyatos‐León, Raquel, et al. “Effects of exercise‐based interventions on postpartum depression: A meta‐analysis of randomized controlled trials.” Birth 44.3 (2017): 200-208.
Hinman, Sally K., et al. “Exercise in pregnancy: a clinical review.” Sports health 7.6 (2015): 527-531.