Maternal Obesity from All Sides

[Editor’s note: This week and next on Science & Sensibility, we will discuss the issue of maternal obesity.  With increasing numbers of overweight and obese women approaching pregnancy, labor and birth, complication and intervention rates are sky rocketing in this population—in sometimes controversial ways.  This series of posts will attempt to answer the ultimate question:  how do we tenderly care for these women, employ evidence-based practices, and still support and honor normal birth whenever possible?]

Globesity:  A World-Wide Epidemic
Maternity care providers bemoan the increased risks associated with caring for overweight and obese pregnant women.  The recipients of their care feel unfairly judged, overly intervened-upon and ghettoized for their body habitus.  As this issue continues to grow, maternity care providers, doulas and childbirth educators need to find a way to interact with these women with equal amounts of compassion and scientific evidence.  And the evidence, in and of itself, is sometimes controversial.

As it turns out, maternal overweight and obesity isn’t just an American thing anymore.  The World Health Organization has made a surveillance tool available on their website, where you can view charts, graphs and maps detailing the rates of adult obesity by country.  Here in America, nearly 36% of adults are obese, including 1 out of 3 women.  The UK reports a similar rate, with 34% of adults considered obese, including 1 out of 5 women.  And pregnant American women are found to be obese 18-38% of the time.

While different countries sometimes use different methods to categorize weight status, the Body Mass Index calculator is most commonly employed:


The problem with using BMI as a body weight categorization tool, is that it does not take into account bony structure, muscle mass or percentages of lean mass compared to adipose tissue.  At best, Body Mass Index is a crude measure of health.  However, academic literature that analyzes weight in relation to pregnancy outcomes typically uses BMI (pre-pregnancy, first prenatal appointment weight or weight at time of delivery) as a primary indicator for study group categorization.

Not only do studies use BMI to include or exclude study participants, but reports have recently emerged that some medical practices are also using BMI as a screening tool: for either accepting or rejecting patients altogether.

The Baltimore Sun recently reported on a slowly emerging trend in southern Florida, in which some maternity care practices are turning away potential new patients, if they weigh more than, say, 200 pounds.  Other doctors practicing in the same area admonish their colleagues for maintaining such policies, despite the increased risk for pregnancy, labor and birth complications many in the industry believe to be an inherent part of attending pregnant women of size.

Other obstetricians, like Dr. Cynthia Maxwell at the University of Toronto Department of Obstetrics & Gynecology, are implementing clinical changes with the aim to improve treatment of and outcomes for overweight expectant mothers, as outlined in this SOCG clinical practice guideline (for which Dr. Maxwell was a principal author).

What the Evidence Shows:  Risks Associated with Maternal Obesity
The basis for heightened concern—whether fueling the exclusion of certain women from their practices, or adopting new approaches to their patient care in response to the growing obesity epidemic—is in the list of complications that are known to coexist with maternal overweight, obesity and morbid obesity.  It should be noted that these weight categories are not all equivalent, and that many of the risk factors we will cover here, and in subsequent posts, become riskier the more overweight or obese an expectant woman is.

In Dr. Tahir Mahmood’s article, Review:  Obesity and pregnancy: an obstetrician’s viewa compilation of statistics from twenty different papers on the subject (British Journal of Diabetes and Vascular Disease 2009; 9: 19-22)—Table 1 provides a an overview of some of the problematic conditions that can be associated with pregnancy in the overweight and obese population:

Other concerns, not listed in this table, but discussed elsewhere in Mahmood’s aricle, as well as in other recent literature include:

-gestational Diabetes (GD)
-fetal macrosomia  (birth weight >4,000g)
-difficulty fighting postpartum infections
-maintained overweight/obesity between pregnancies
-prolongation of pregnancy/increased likelihood to deliver postdates
-other short and long term impacts on fetus/infant/child (neural tubes defects, lifetime increased risk of diabetes and obesity…)
-increased risk of stillbirth
-increased risk of maternal mortality
-postpartum hemorrhage

Complicating this issue beyond the fear factor of increasing a woman’s risk of, say, postpartum hemorrhage or fetal loss…is the fact that statistically, the morbidities associated with maternal weight are less than a slam dunk.  While many women of size will go on to develop one or more of the above-listed complications, some of these women will go on to experience completely normal pregnancies, labors and births. At the same time,  some normal–or underweight–women will go on to develop significant morbidities not typically associated with women boasting BMIs less than 25.

For the professionals working with these women during (or, hopefully, before) their pregnancies, the challenge becomes finding a way to communicate the gravity of these possibilities, without assuming every overweight expectant mother is a ticking time bomb—and all the while treating all expectant mothers with the best evidence-based care, no matter what their size.

[In tomorrow's installment of this series, we will look at some of the particular co-morbidities associated with maternal overweight/obesity, and the types of provider interactions and interventions that evidence does--and does not--support.]

Posted by:  Kimmelin Hull, PA, LCCE

Maternal Obesity, Uncategorized , , , , ,

  1. avatar
    June 6th, 2011 at 08:56 | #1

    It is very interesting to read the true complications that can arise from being obese or overweight. In my VBAC attempt, the doctors that back-up my midwives did not want to allow me to VBAC because of my weight. I was told to limit my weight gain by eating a diet of vegetables, whole grains, little to no fruit, and high protein. This is an excellent, healthy diet and I lost weight during my pregnancy. However, they continued to use “fear tactics” to persuade me not to VBAC. The reasons they presented to me as to why VBAC would be dangerous is where I find fault. I was told that if I had more fat layers in my belly, an emergency c-section would be more difficult. No mention of increased risk like mentioned above in your chart. Instead of feeling shamed for my weight, I would have been more likely to analyze my actual risks, had they been presented to me logically and factually.

  2. June 6th, 2011 at 10:07 | #2

    Thank you for sharing your story with us, Marybeth!

  3. June 6th, 2011 at 10:24 | #3

    Wonderful work, and essential information to have a conversation about how we approach helping. I look forward to hearing more about the underlying psychosocial implications. Thanks, Kimmelin

  4. June 6th, 2011 at 11:14 | #4

    Thank you so much for your balanced article. Yes obease women are at higher risks for pregnancy complications but not all obease women incur these risks. Last year I, as a “morbidly obease” woman, had a very healthy pregnancy with no complications due to my size and had a natural childbirth. My experience was transformative and gave me a whole new apprecaition for my body. I was blessed to have such a supportive medical team with my midwife who never considered me “high risk” and my doula who had more faith in my body then I had. Through this expereince I’ve started advocating for plus size women and have started a project linking doulas to plus size women. Doulas help to decrease the risk of c-sections and statically obease women are more pronte to them. I’m truly looking forward to reading more and if you’re interested in the work I’m doing please check out my website http://www.plussizebirth.com.

  5. June 6th, 2011 at 11:48 | #5


    Thank you for sharing your link with us! Congratulations on your wonderful birth!

  6. avatar
    June 6th, 2011 at 12:07 | #6

    Thank you very much for the Chart. It helps put things into perspective.

  7. June 6th, 2011 at 12:12 | #7

    I think the last paragraph in this article sums it right up – providing knowledge and education to expecting mothers is key. My son is 7 months old, and while I would be considered obese, I had a very healthy pregnancy, labour and delivery. Towards the end of my pregnancy, I had mild hypertension (experienced no symptoms aside from high readings) which led to an induction, which considering how some inductions CAN go, mine went very well. I remained healthy and active, for the sake of my unborn child as well as myself, and was not considered ‘high risk’ throughout my pregnancy. I am now an avid birth information junkie and actively seek out blogs and articles on achieving safe childbirth, natural childbirth, as well as seeking out additional support systems, such as a doula and/or midwife. I believe more than ever in the power of my own body, but not even just that, I believe more than ever in the power of my own mind, to work alongside my body in achieving what I want to and need to achieve, both in terms of childbirth as well as general life issues. :)

  8. June 6th, 2011 at 14:45 | #8


    The empowerment you describe–not only relating to birth, but now to life in general–is a wonderful result of birthing practices in which the woman remains informed and integral to the decision-making process. Glad to know you experienced such a great outcome with your son’s pregnancy and birth!

  9. avatar
    June 8th, 2011 at 21:20 | #9

    i am an obese woman who has carried 5 children to term and had home births with all five including my first, a set of twins. i never have had any of the above complications. Purely anecdotal I know, but I have been judged by these charts. I wonder at some of the above figures. More inductions alone, could lead to more c-sections, hemorrhage,infections and deaths. Is it really inherently riskier to be obese, or is the preconceived idea of fat and obesity that leads to the higher risks?

  10. avatar
    June 10th, 2011 at 11:38 | #10

    Is there an error in the table? The risk of a fetus >4000g is listed as higher for “normal” weight patients than for any of the overweight categories. I didn’t think that was correct?

  11. June 10th, 2011 at 15:58 | #11

    May be so, unless their compiled data set came out differently than other studies. Would be great to contact the journal or lead study author and ask the same question.

  12. avatar
    June 13th, 2011 at 17:01 | #12

    One other complication when it comes to tracking “dangers” for overweight mothers is that of self-fulfilling medical prophecies. Doctors who read or hear that there is a greater likelihood of some complication may limit options, demand preemptive treatments, or intervene sooner than they would for an average-weight mother. For instance, overall risk of cesarean rises with size, but is this because overweight mothers are not able to birth vaginally, or because they are not ALLOWED to birth vaginally? Risk of postpartum hemmorage increases, but is this related to high-intervention practices during the birth, or to something innately problematic with their weight?

    In light of this, how do we analyze statistics like these? How can we try to determine what is a “normal” complication for overweight mothers when they are not being allowed to birth “normally”?

  13. avatar
    June 13th, 2011 at 17:07 | #13

    It could be because of an increase in induction. Doctors who “know” that overweight mothers are likely to birth large babies could be more likely to recommend an early induction, or less likely to allow the pregnancy to continue past the due date. You might also notice that the likelihood of pregnancy continuing past 41 weeks drops in morbidly obese women, even though it is listed as one of the complications in overweight mothers.

    This is exactly what I was questioning in my later comment – how can we know if these statistics indicative of “normal” complications of pregnancy in overweight mothers, or if they are skewed by the care overweight mothers receive?

  14. avatar
    June 16th, 2011 at 07:57 | #14

    @Sarah, I absolutely agree with that. There seems to be evidence that obesity, at least significant obesity, increases the risk for some complications, but we all need to be careful not to assume that correlation implies causation. I wonder about this too for older mothers. Are they more likely to have a cesarean because of complications due to their age, or because care providers are more likely to intervene?

  15. June 16th, 2011 at 09:57 | #15

    I recently wrote a post about “advanced maternal age” and the unfair “risks” associated therein:

  16. August 21st, 2011 at 09:00 | #16

    People don’t truly understand the risks of being overweight. Why do most want to lose weight? Most would say to look better. Looking better certainly is a benefit of losing weight, but this shouldn’t be the sole reason to lose weight. There is a 1000 pound gorilla in the room and it’s often ignored. Being overweight for a long period of time kills thousands of people each year

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