Sunday, May 25, 2014

Prenatal Vitamins, Pre-Eclampsia, and Obesity

Image from Wikimedia Commons
Here is the abstract for a recent study that found that use of a prenatal vitamin in the first trimester of pregnancy substantially reduced the risk for development of pre-eclampsia, especially in "overweight" and "obese" women. 

The most intriguing finding of the study was that taking a prenatal vitamin in the first trimester lowered the risk for pre-eclampsia by 55% in "overweight" women, and by 62% in "obese" women. 

Surprisingly, only about 1/3 of women of any size in this study actually took a prenatal vitamin during the first trimester. Other studies of relatively affluent first-world countries show that only about 30-60% of women routinely took prenatal vitamins before or in the first trimester. This is why improving prenatal vitamin use is a public health intervention which could have significant potential impact. 

This may be especially true in obese women, since women of size tend to have lower rates of prenatal or preconception supplement use (45% vs. 60% in one study). 

The $64,000 question is whether we can lower pregnancy complication rates in obese women by encouraging them to routinely take prenatal vitamins, even when not actively trying to get pregnant.

Caveats to the Study

The findings of this study are intriguing and deserve to be followed up. However, keep in mind that this is a relatively small study and that these results need to be duplicated multiple times before a true correlation can be established.

Also keep in mind that other studies on prenatal vitamin use (multiple or single vitamins) in the overall population have found more ambivalent results or even poorer outcomes with routine supplementation. 

So it's important not to over-interpret this one study or make broad policy recommendations based on it.

Still, it was significant that prenatal vitamin use made such a difference in women of size in this study. Why might this be?

Research suggests that many women of size have nutrient deficiencies such as low vitamin D, and some research suggests that low levels of vitamin D or other nutrients may be associated with higher risk for pre-eclampsia, so this could be explain why prenatal vitamin use was so helpful. However, not all research supports such an association, so again, caution is needed. 

It might be that supplementation is most beneficial only for those with significant nutrient deficits. A more sensible policy might be routine pre-conception nutrient testing for those most at risk rather than routine supplementation across the board for everyone. 

Since obese women are at significant risk for pre-eclampsia and certain birth defects, pre-conception nutrient testing is something that women of size who are considering pregnancy might want to consider. 

Personally, I favor pre-conception testing and emphasizing the use of whole foods and excellent nutrition as the best approach to lowering the risk for complications in women of size. 

To me, the best approach is always to emphasize nutrition before pills. I think artificial pills only go so far in helping nutrient deficiencies, and vitamin supplements of one or two particular vitamins can sometimes induce imbalances of other vitamins or minerals. Frankly, focusing on increasing dietary intake of fruits and vegetables may be the safest way to improve nutritional status and decrease risks before and during pregnancy.

Still, there is a place for vitamins and/or medications at times. A prenatal vitamin before pregnancy and during the first trimester might be helpful for many people. It seems like a common-sense public health strategy that might help and is at minimal risk for harm if it's done in moderation.

But the bottom line is that we need more studies showing the effect of routine prenatal vitamin use in subgroups such as overweight and obese women. I would particularly like to see research stratified by class of obesity, nutritional intake, pre-conception nutrient status, and insulin resistance status so we could have a more nuanced examination of potential confounders as well. 

Only when such nuanced research is done will we truly know for sure whether routine pre-conception and prenatal vitamin supplementation is an effective strategy for lowering the risk of complications in women of size. 


Matern Child Nutr. 2014 May 22. doi: 10.1111/mcn.12133. [Epub ahead of print] First trimester multivitamin/mineral use is associated with reduced risk of pre-eclampsia among overweight and obese women. Vanderlelie J1, Scott R, Shibl R, Lewkowicz J, Perkins A, Scuffham PA. PMID: 24847942
The use of pregnancy-specific multivitamin supplements is widely recommended to support maternal homeostasis during pregnancy. Our objective was to investigate whether multivitamin use during pregnancy is associated with a reduced risk of pre-eclampsia. 
The effect of multivitamin use on incidence of pre-eclampsia in lean and overweight/obese women was analysed using data collected between 2006 and 2011 as part of the Environments for Healthy Living Project, Griffith University, Australia. A total of 2261 pregnancies were included in the analysis with pre-eclampsia reported in 1.95% of subjects. 
Body mass index (BMI) ≥ 25 was associated with a 1.97-fold [95% confidence interval (CI): 0.93, 4.16] increase in pre-eclampsia risk. First trimester multivitamin use was reported by 31.8% of women and after adjustment, was associated with a 67% reduction in pre-eclampsia risk (95%CI: 0.14, 0.75). 
Stratification by BMI demonstrated a 55% reduction in pre-eclampsia risk (95%CI: 0.30, 0.86) in overweight (BMI: 25-29.9) and 62% risk reduction (95%CI: 0.16, 0.92) in obese (BMI: ≥30) cohorts that supplemented with multivitamins in the first trimester of pregnancy. This finding may be particular to the Australian population and reflect inherent nutritional deficits. 
First trimester folate supplementation was found to reduce pre-eclampsia incidence [adjusted odds ratios (AOR) 0.42 95%CI: 0.13, 0.98] and demonstrated significance upon stratification by overweight status for women with BMI >25 (AOR 0.55 95%CI: 0.31, 0.96). These results support the hypothesis that multivitamin supplementation may be beneficial in reducing the incidence of pre-eclampsia during pregnancy and be of particular importance for those with a BMI ≥25.


  1. So I had a fun experience with my second pregnancy. I had an ovarian cyst (long story, I got featured on My OB Said What!) that ended up getting removed at 30 weeks. The week after I came home from the hospital, I dropped 15lbs and was having numerous bowel movements a day, I also complained of being very easily short of breath, as in just standing for a few minutes would knock the wind out of me. Both my midwife and surgeon brushed it off, because ya know, I'm fat and even if I'm not eating enough to grow a baby and recover from major adominal surgery at the same time, it's not like I don't have plenty of nutrients stored up! I knew they were full of shit from reviewing all of the research you've posted here, but they both insisted it was fine and I was just exhausted so I dropped it. The shortness of breath never went away, and over the next 6 weeks, my health deteriorated. My blood pressure was up, my feet and hands were swelling, I was getting light headaches, and my vision was a bit blurred. Warning bells for the midwives, right? No protein in urine though, and I argued round and round about my BP because I knew they were using the wrong cuff. They sent me off for blood work and found out my ferritin level was almost low enough to risk me out of a homebirth. I took double the recommended dosage of Floradix and my symptoms disappeared. Had I been seeing a doctor, I'm fairly certain I would have been pressured into induction for pre-e, even without definitive proof. It was a very interesting experience for me though, to find out that you can develop nearly every symptom of pre-e just from having low iron, and I don't doubt there are similar expamples of being low in other nutrients causing the same problems.

  2. Cassandra, what was your ferritin level, just out of curiosity?

  3. And did you lose a lot of blood with the ovarian cyst surgery? That would certainly be a risk factor for anemia that they should have checked.

  4. I think it was 11 and the cut off was 8 or 9, I never got those labs printed so not positive, I've gotten numbers screwed up before. I just remember at one point having this huge panic attack because I felt so horrible, my heart was racing, I was tingling all over, it was awful. Immediate relief of symptoms after taking a big dose of iron. If I had heavy blood loss, nobody told me. My post op follow up care was basically non-existent.

    Another fun story - when I was in the hospital, they used the automatic BP cuffs and kept commenting that my BP was elevated (140/90) and I argued with them the first few times because I knew the cuff was too small. Eventually I stopped saying anything, but I was also on heavy pain drugs and didn't care. I even remember coming out of the anesthesia and hearing my mom and husband arguing with the nurse checking me back into my room that she was using the wrong size cuff and my BP was probably just fine, because I've ranted about it so many times to them! I was there 5 days with 6 BP checks a day before one nurse finally goes "Oh we've been using the wrong one!" so she checks it on my forearm and says "Well it's the same as on your upper arm so it must be fine," and I facepalmed so hard.

  5. Those levels sound more like your hemoglobin rather than your ferritin, although it could be ferritin too. They don't routinely test ferritin, though. But hemoglobin is a marker they do test frequently in pregnancy, with cutoffs similar to what you mention.

    Either way you're anemic, but there are different types of anemia. Low ferritin is harder to treat because it's about stored iron. Low hemoglobin is usually pretty responsive to things like Floradix.

    So once your levels came up, your PE symptoms went away and everything was okay that pregnancy?

  6. Within one day of taking Floradix all of my symptoms had lessened significantly and were gone within a few days. I continued taking it until two large bottles were gone, that stuff is expensive. Part of why my midwives didn't automatically test me is because I have a meat heavy diet and they just didn't suspect it, until I complained about my pica coming back (off and on since young teens). When the labs came back for low ferritin, I looked up symptoms and they were dead on. Everyone just kept thinking PE and didn't even notice that the symptoms are similar. I was on 3 days of IV abx in the hospital which destroyed my gut flora and I wasn't absorbing any nutrients while trying to simultaneously put weight on my baby and heal from a big surgery. How is weight loss + frequent cream colored bowel movements not a red flag during pregnancy??? Ended up with a completely normal homebirth, almost no blood loss. Baby was 10lb10oz 23in, no complications. He's 6 months old as of yesterday!