What is the effect of having had an eating disorder on pregnancy? And more specifically, are women who’ve had eating disorders more likely to experience perinatal and delivery complications?
Like with a lot of things, the information out there is mixed. (This is why one study is never enough and replication is crucial.) Early studies seemed to have suggested that women with EDs face an increased risk complications during the last stage of pregnancy and during delivery. On the other hand, subsequent studies done with larger clinical samples didn’t find any major differences between women with and without (a history) of eating disorders.
The authors summarize the current state of knowledge:
In short, the available evidence suggests that both active and past maternal [anorexia nervosa] may be associated with a decreased birth weight and that maternal ED might be associated with pregnancy and postnatal complications. Methodological limitations of previous studies, i.e. small and unrepresentative clinical studies, small number of cases identified, low representation of ethnic minorities, highlight the need for replication and extension of findings.
A total of 5256 women were eligible to participate in the current study. They asked the women whether they had ever (and in the past year) suffered from a list of psychiatric disorders, including anorexia and bulimia nervosa:
- 112 women (2.1%) reported having ever suffered from AN, and 17 (0.3%) in the last year;
- 160 (3.0%) reported having ever suffered from BN and 49 (0.9%) in the last year;
- 93 (1.8%) reported having suffered from both ED (AN + BN) ever and seven (0.1%) in the last year.
Combining the two groups (having ever suffered from + suffering in the past year):
- lifetime AN: 129 women (2.4%)
- lifetime BN: 209 women (3.9%)
- lifetime AN+BN: 100 women (1.9%)
The other two groups were women who suffered from “other psychiatric disorders” (depression, anxiety, psychosis and manic episodes, but not EDs): 1002 women or 19.1%. This left 3816 or 72.6% in the “unexposed group.”
The authors took detailed information about educational background, ethnicity, prepregnancy weight, income level, smoking habits and alcohol consumption. I’ll spare you the details but feel free to ask me if you are interested.
SUMMARY OF MAJOR FINDINGS
- ~15% of all women had some perinatal complications – no differences between groups
- no significant differences were seen between groups for: pre-eclampsia [hypertension which arises during pregnancy], hospitalization during pregnancy, spontaneous delivery and postnatal complications
- there was “borderline evidence” (as the authors put it) that women with AN had higher prevalence of suspected fetal distress. Suspected because they just evaluated fetal blood pH. To be more specific here is how the numbers break down: AN: 11.6%; BN: 6.7%; AN+BN: 9%; other psychiatric disorders: 8.5%; unexposed group: 7.3%
- some evidence that women with lifetime AN gained more weight overall compared to other groups (on average ~2lbs more, but they also started at a lower weight, on average, than all the other groups)
Birth weight, SGA (small-for-gestational-age) and prematurity:
- no differences between mean birth weight or SGA among all groups
- no differences in the frequency of premature births (but a trend toward increased frequency in the AN+BN group compared to the unexposed group, but this was not significant)
Overall pretty good news, I think.
Previous research on perinatal complications in relation to maternal ED has been inconclusive, with small clinical studies reporting increased risk of perinatal complications and larger general population studies finding no associations. The present study confirms findings from these larger studies in relation to perinatal complications and prematurity.
Why the disparity between small clinical studies and large population-based studies? There are many reasons, and Micali et al offer some:
- small clinical studies => sample women more likely to be actively ill with ED => possibly higher risk of complications
- low prevalence of some perinatal complications = even large population-based studies have limited ability to detect differences between groups
The nice thing about this study is that to the greatest extent possible, outcomes were measured objectively. For example, that means that weight gain during pregnancy was evaluated by the authors–not self-reported and not done in retrospect as is the case with many other studies. This means that the chances of bias (in this regard, at least) are small.
Despite the numbers, this study was still too small to detect differences between groups for very rare outcomes. This means that in future, and hopefully larger studies, what was trending toward significance in this study might reach significance (or it might not, if this is just a ‘blip’ – a false alarm).
Keep in mind, the prepregnancy body mass index (BMI, this was self-reported) for women with lifetime AN was 22.2; lifetime BN: 24.5; AN+BN: 22.5; and 23.5 for both “other psychiatric” and “unexposed” groups. So overall, women with lifetime AN were weight-restored and didn’t differ from the other groups in this regard. This is an important point to keep in mind when thinking about these findings.
What I take away from this is that overall, a history of anorexia nervosa and bulimia nervosa, provided you are weight-restored and relatively healthy, will not significantly affect pregnancy outcomes. If we were to compare women with AN who got pregnant while underweight, we might see quite different results (which is what previous small clinical studies suggest, according to the authors).
I’ve tried to keep this post short, so let me know if you have any questions about the demographic characteristics of the study population or anything else.
Oh and by the way, notice the huge difference between self-reported rates of eating disorders in this study (which are fairly close to the reported prevalence rates in other studies) and the study I blogged about last time (where 25% of bisexual women reported having had an eating disorder). Yes, this study didn’t look at binge eating disorder (which is more prevalent than AN and BN), but still I think it is an interesting observation.
To be honest, I’m not sure why there is such a disparity between these self-reported numbers. It may be that the vignettes Micali et al included to explain exactly what they mean by each disorder had an effect – or it could be that 25% of bisexual women had eating disorders. It is hard to tell by just looking at one study.
Personal note: My apologized for the dearth of posts in October. I have finished thesis writing and most of it has been edited by my boss, so I just need to have one more committee meeting and then defend. All of this means that I now have more time to blog!
Micali, N., De Stavola, B., Dos-Santos-Silva, I., Steenweg-de Graaff, J., Jansen, P., Jaddoe V, Hofman A, Verhulst F, Steegers E, & Tiemeier H (2012). Perinatal outcomes and gestational weight gain in women with eating disorders: a population-based cohort study. BJOG: An International Journal of Obstetrics and Gynaecology, 119 (12), 1493-1502 PMID: 22901019