Preconception Body Mass Index (BMI) Health Outcomes

Lifestyle factors such as body mass index (BMI) can affect your ability to conceive and also impact your unborn child’s health – long term.

One way we assess your health is knowing your body mass index (BMI). This metric simply takes into account height and weight. While there are many factors to assessing health, we do recommend being within a healthy BMI range.

Being at a weight-level that is a BMI of 19 or less can result in irregular or absent periods and the lack of ovulation.

Did you know that maternal nutrition before and during pregnancy is recognized as being an important factor for your child’s health both physically and intellectually?

Having low maternal weight at pre-pregnancy affects your unborn child and is associated with an increased risk of undernutrition and a decrease in intellectual domains such as verbal comprehension index amongst children. This is important to know and if you’re underweight and experience irregular periods, you may need to gain weight.

Being overweight, or a BMI of 27 or higher can disrupt regular egg development and ovulation. And obesity is associated with an increased risk of almost all pregnancy complications.

These can include but are not limited to preeclampsia, gestational diabetes, delivery of a large for gestational age baby (LGA baby) and a higher incidence of congenital defects all occur more frequently than in women with a normal BMI. Obesity increases a woman’s chance of having a baby with a heart defect by 15%. The risk increases with rising obesity. Moderately obese women are 11% more likely to have a child with a heart defect, and morbidly obese women are 33% more likely. This can be devastating and is one reason why preconception health and management is so important to both the mother and unborn child.

Research shows that a healthy body weight improves a woman’s chances of conception, whether naturally or through fertility treatments like IVF. Want another reason to watch the scale?  Women who in a normal range of BMI also have better IVF outcomes. It’s not just women! Research also show that overweight male partners may lengthen a couple’s time to conception. And what’s even better, starting your pregnancy at a healthy weight also lowers risks of complication for mom and baby both during pregnancy and delivery.

We’d love to hear: Have you been able to manage your weight or would additional support in this area help you?

If you’re looking for additional support from Registered Dietitians and Nurses, we’d love for you to join us and other moms optimizing their ability to conceive. Keep in mind that the most successful infertility approaches include groups that offer weight management, stress reduction and social support. Women who utilize stress reduction techniques and lower their stress levels achieve higher pregnancy rates. Are you looking for a preconception support group? Unique Footprints has support groups for preconception, pregnancy, postpartum and through the transition into motherhood and we’d love for you to join us.



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Unique Footprints Authors:

Caroline Susie, RD/LD

Caroline is in private practice and is the Unique Footprints Registered Dietitian, mother of a 6 month old and two Jack Russel Terriers. She helps women sort through nutrition trends to find the best evidence-based nutrition approach for their lifestyle. She currently specializes in prenatal and postnatal nutrition and believes that taking a personalized approach is best. She is a contributor for Fox News and many other publications. Personally, Caroline is a fitness enthusiast who enjoys running, yoga, tennis and is a lover of food. You can learn more about Carline here. 

Jenny Morrow, RN, IBCLC, LCCE, RYT

Jenny is a born and raised Texan who loves the feel of a book in her hands, an unshakable optimistic and refuels by time in nature. She’s a mom, neonatal nurse and founder of Unique Footprints (a fully realized, 100% digital pregnant and new mom resource). She created her company in the delivery room – literally! As a nurse assisting with deliveries and postpartum care, she directly witnessed families who did not feel prepared and were shocked through the transition into parenthood, and she knew there was a better way. Jenny has taught over 10,000 expecting families how to prepare for this time in their lives. You can learn more about Jenny here.


Chaudhry, S. H., Taljaard, M., MacFarlane, A. J., Gaudet, L. M., Smith, G. N., Rodger, M., Rennicks White, R., Walker, M. C., & Wen, S. W. (2019). The role of maternal homocysteine concentration in placenta-mediated complications: findings from the Ottawa and Kingston birth cohort. BMC pregnancy and childbirth19(1), 75.

Min, Y., Wang, X., Chen, H., & Yin, G. (2020). The exploration of Hashimoto’s Thyroiditis related miscarriage for better treatment modalities. International journal of medical sciences17(16), 2402–2415.

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