Pregnancy outcomes of women with and without a history of anorexia nervosa

Maternal Eating Disorders and Adverse Birth Outcomes: A Systematic Review and Meta-Analysis

Previous systematic reviews have reported on the relationship between eating disorders (EDs) and birth outcomes, but there are no existing meta-analyses on this topic. This systematic review and meta-analysis examines the association between lifetime maternal EDs, including anorexia nervosa (AN), bulimia nervosa (BN), and binge-eating disorder (BED) with low birth weight (LBW), preterm birth (PTB), small for gestational age (SGA), large for gestational age (LGA), and miscarriage. Four databases were systematically searched for quantitative literature on maternal EDs that preceded birth outcomes. Eighteen studies met the inclusion criteria and were included in the review. The meta-analyses included 6 studies on miscarriage, 11 on PTB, 4 on LBW, 9 on SGA, and 4 on LGA. The Mantel-Haenszel random effects model was used to test the associations between EDs and birth outcomes. The results showed significant positive associations between AN and LBW (OR 1.74, 95% confidence interval (CI) 1.49, 2.03), AN and SGA (OR 1.39, 95% CI 1.17, 1.65), BN and PTB (OR 1.19, 95% CI 1.04, 1.36), and BED and LGA (OR 1.43 95% CI 1.18, 1.72). EDs were not significantly correlated with miscarriage. These findings reveal the importance of screening for and treating EDs in pregnant women.

Trajectories of severe eating disorders through pregnancy and early motherhood

Background

During pregnancy and early motherhood, risks of relapse and worsening are high for women with a history of eating disorders (EDs), as are adverse sequelae for their babies. However, systematic descriptions of the processes that these women undergo through pregnancy, birth, and early motherhood are lacking, as are good descriptions of the various trajectories these women follow through pregnancy and early motherhood. This study addresses both these knowledge gaps.

Methods

We used a longitudinal research interview design, recruiting a non-clinical sample of 24 women with a history of severe EDs from routine pregnancy controls in five public, local, family health care centers in Norway. The participants were interviewed twice, first during pregnancy and then 4-6 months after delivery. Data were analyzed according to grounded theory. The focus was on modeling the trajectories of EDs through pregnancy, birth, and early motherhood. All the participants were diagnosed (DSM-5) using the Eating Disorder Examination and then completed the Eating Disorder Examination Questionnaire.

Results

Five perceived trajectories through pregnancy and early motherhood were identified: "The mastering mother," in which an ED pathology seems to be absent through pregnancy and early motherhood; "The inadequate mother," in which the ED pathology worsens before pregnancy, through pregnancy, and early motherhood; "The overwhelmed mother," in which the ED worsens during pregnancy and early motherhood; "The depressed mother," in which the ED is put on hold during pregnancy, but worsens in early motherhood; and "The succeeding mother," in which the ED worsens during pregnancy, but reduces in early motherhood.

Discussion

ED trajectories through pregnancy and early motherhood vary greatly among women with a history of EDs. This may indicate different psychological dynamics through these phases. A model with five trajectories captures a large degree of the variation. The model may help clinicians' preparedness when dealing with these patients.

Adverse live-born pregnancy outcomes among pregnant people with anorexia nervosa

BACKGROUND

Previous findings related to the association of adverse pregnancy outcomes with anorexia nervosa are mixed.

OBJECTIVE

This study aimed to investigate the association of adverse live-born pregnancy outcomes with anorexia nervosa using adjustment modeling accounting for confounding factors, and a mediation analysis addressing the contribution of underweight prepregnancy body mass index and gestational weight gain to those outcomes.

STUDY DESIGN

The sample included California live-born singletons with births between 2007 and 2021. The administrative data set contained birth certificates linked to hospital discharge records. Anorexia nervosa diagnosis during pregnancy was obtained from International Classification of Diseases codes on hospital discharge records. Adverse pregnancy outcomes examined included gestational diabetes, gestational hypertension, preeclampsia, anemia, antepartum hemorrhage, premature rupture of membranes, premature labor, cesarean delivery, oligohydramnios, placenta previa, chorioamnionitis, placental abruption, severe maternal morbidity, small for gestational age, large for gestational age, low birthweight, and preterm birth (by timing and indication). Risk of each adverse outcome was calculated using Poisson regression models. Unadjusted risk of each adverse outcome was calculated, and then the risks were adjusted for demographic factors. The final adjusted model included demographic factors, anxiety, depression, substance use, and smoking. A mediation analysis was performed to estimate the excess risk of adverse outcomes mediated by underweight prepregnancy body mass index and gestational weight gain below the American College of Obstetricians and Gynecologists recommendation.

RESULTS

The sample included 241 pregnant people with a diagnosis of anorexia nervosa and 6,418,236 pregnant people without an eating disorder diagnosis. An anorexia nervosa diagnosis during pregnancy was associated with many adverse pregnancy outcomes in unadjusted models (relative risks ranged from 1.65 [preeclampsia] to 3.56 [antepartum hemorrhage]) in comparison with people without an eating disorder diagnosis. In the final adjusted models, birthing people with an anorexia nervosa diagnosis were more likely to have anemia, preterm labor, oligohydramnios, severe maternal morbidity, a small for gestational age or low-birthweight infant, and preterm birth between 32 and 36 weeks with spontaneous preterm labor (adjusted relative risks ranged from 1.43 to 2.55). Underweight prepregnancy body mass index mediated 7.78% of the excess in preterm births and 18.00% of the excess in small for gestational age infants. Gestational weight gain below the recommendation mediated 38.89% of the excess in preterm births and 40.44% of the excess in low-birthweight infants.

CONCLUSION

Anorexia nervosa diagnosis during pregnancy was associated with a number of clinically important adverse pregnancy outcomes in comparison with people without an eating disorder diagnosis. Adjusting for anxiety, depression, substance use, and smoking during pregnancy decreased this risk. A substantial percentage of the excess risk of adverse outcomes was mediated by an underweight prepregnancy body mass index, and an even larger proportion of excess risk was mediated by gestational weight gain below the recommendation. This information is important for clinicians to consider when caring for patients with anorexia nervosa. Considering and treating anorexia nervosa and comorbid conditions and counseling patients about mediating factors such as preconception weight and gestational weight gain may improve live-born pregnancy outcomes among people with anorexia nervosa.

Pregnancy outcomes in women with anorexia nervosa: a population-based study and analysis of a matched cohort

RESEARCH QUESTION

What implications does anorexia nervosa have on pregnancy outcomes in a US population?

DESIGN

A retrospective, population-based study using data from the Healthcare Cost and Utilization Project-Nationwide Inpatient Sample. A dataset of all deliveries between 2004 and 2014 inclusively was created. The population was divided into women with anorexia nervosa (n = 214) and women without anorexia nervosa (n = 9,096,574), and a cohort matched 1:4 with anorexia nervosa for age, race, medical insurance type and income quartile. Delivery and neonatal outcomes were compared between the two matched groups and with the control group of deliveries. A multivariable logistic regression analysis, controlling for statistically significant baseline characteristics, explored associations between anorexia nervosa and delivery, and neonatal outcomes.

RESULTS

Compared with the entire group, women diagnosed with anorexia nervosa were more likely to be white, smokers, of higher income or diagnosed with another psychiatric disorder. In the unmatched comparison, women with anorexia nervosa had a higher frequency of preterm delivery (adjusted odds ratio [aOR] 2.98 CI 1.86 to 4.76, P < 0.001), placental abruption (aOR 3.41 CI 1.38 to 8.40, P = 0.008) and small for gestational age (SGA) neonates (aOR 5.32 CI 3.12 to 9.09, P < 0.001). In the matched comparison, preterm delivery (aOR 5.31, CI 3.02 to 9.32, P < 0.001) and SGA neonates were significantly higher in the anorexia nervosa group (aOR 4.69 CI 2.6 to 8.41, P < 0.001), providing results similar to the unmatched comparison.

CONCLUSION

Healthcare providers, specifically fertility specialists, should be aware of the magnitude of adverse outcomes related to pregnancy in women with anorexia nervosa.

Eating Disorders in Children and Adolescents: A Practical Review and Update for Pediatric Gynecologists

Eating disorders (EDs) are common among female adolescents and young adults and can have serious and diverse health consequences. Pediatric gynecology providers have the opportunity to play a vital role in the recognition of EDs in this population. Early medical detection and referral for appropriate evidence-based treatment can lead to better health outcomes for youth. In this article we aim to increase the awareness of the pediatric gynecologist of typical and subtle presentations of EDs, provide guidance for screening, discuss common and serious medical complications, and review treatment considerations for gynecologic issues in patients with EDs.

Eating disorders are associated with adverse obstetric and perinatal outcomes: a systematic review

Objective:

To systematically review the literature focusing on obstetric and perinatal outcomes in women with previous or current eating disorders (EDs) and on the consequences of maternal EDs for the offspring.

Methods:

The study was performed following the systematic review and meta-analysis (PRISMA) statement. PubMed, SciELO, and Cochrane databases were searched for non-interventional studies published in English or Portuguese from January 1980 to December 2020. Risk of bias was assessed using the Methods guide for effectiveness and comparative effectiveness reviews (American Agency for Healthcare Research and Quality).

Results:

The search yielded 441 records, and 30 articles were included. The psychiatric outcome associated with EDs in women was mainly perinatal depression. The most prevalent obstetric outcomes observed in women with EDs were vomiting, hyperemesis, bleeding, and anemia. Most studies found maternal anorexia nervosa and bulimia nervosa to be associated with low birth weight and slow fetal growth. Women with binge EDs delivered children with increased birth weight. Of the 30 studies included, methodological quality was good in seven, fair in eight, and poor in 15 studies.

Conclusion:

A considerable body of evidence was reviewed to assess obstetric and perinatal outcomes in EDs. Acute and lifetime EDs, especially if severe, correlated with poor perinatal, obstetric, and neonatal outcomes. Obstetricians and general practitioners should be vigilant and screen for EDs during pregnancy.

Why can't I exercise during pregnancy? Time to revisit medical 'absolute' and 'relative' contraindications: systematic review of evidence of harm and a call to action

BACKGROUND

Clinical guidelines recommend pregnant women without contraindication engage in regular physical activity. This is based on extensive evidence demonstrating the safety and benefits of prenatal exercise. However, certain medical conditions or contraindications warrant a reduction, modification or cessation of activity due to potential health risks.

AIM

To review and evaluate the evidence related to medical disorders which may warrant contraindication to prenatal exercise.

METHODS

Online databases were searched up to 5 April 2019. Forty-four unique studies that reported data on our Population (pregnant women with contraindication to exercise), Intervention (subjective/objective measures of acute or chronic exercise), Comparator (not essential) and Outcomes (adverse maternal or fetal outcomes) were included in the review.

KEY FINDINGS

We found that the majority of medical conditions listed as contraindications were based on expert opinion; there is minimal empirical evidence to demonstrate harm of exercise and benefit of activity restriction. We identified 11 complications (eg, gestational hypertension, twin pregnancy) previously classified as contraindications where women may in fact benefit from regular prenatal physical activity with or without modifications. However, the evidence suggests that severe cardiorespiratory disease, placental abruption, vasa previa, uncontrolled type 1 diabetes, intrauterine growth restriction, active preterm labour, severe pre-eclampsia and cervical insufficiency are associated with strong potential for maternal/fetal harm and warrant classification as absolute contraindications.

CONCLUSION

Based on empirical evidence, we provide a call to re-evaluate clinical guidelines related to medical disorders that have previously been considered contraindications to prenatal exercise. Removing barriers to physical activity during pregnancy for women with certain medical conditions may in fact be beneficial for maternal-fetal health outcomes.

Pregnancy outcomes in women with anorexia nervosa

OBJECTIVE

Birth outcomes of women with anorexia nervosa are poorly understood. We hypothesized that hospitalization for anorexia nervosa before or during pregnancy is associated with an elevated risk of adverse maternal and infant birth outcomes.

METHOD

We performed a retrospective cohort study of 2,134,945 pregnancies in Quebec, Canada, from 1989 to 2016. The main exposure measure was anorexia nervosa requiring hospital treatment before or during pregnancy. Outcome measures included stillbirth, preterm birth, low birth weight, small-for-gestational age birth, preeclampsia, gestational diabetes, cesarean delivery, and other pregnancy disorders. We computed risk ratios and 95% confidence intervals (CI) for the association between anorexia nervosa and birth outcomes adjusted for maternal characteristics.

RESULTS

Compared with no hospitalization, anorexia nervosa hospitalization was associated with 1.99 times the risk of stillbirth (95% CI 1.20-3.30), 1.32 times the risk of preterm birth (95% CI 1.13-1.55), 1.69 times the risk of low birth weight (95% CI 1.44-1.99), and 1.52 times the risk of small-for-gestational age birth (95% CI 1.35-1.72). The associations with low birth weight and small-for-gestational age birth were more prominent in women hospitalized for anorexia nervosa during pregnancy or within 2 years of delivery. Hospitalization for anorexia nervosa was associated with certain maternal outcomes, including precipitate labor, acute liver failure, and admission to an intensive care unit.

DISCUSSION

Hospitalization for anorexia nervosa before or during pregnancy is associated with adverse infant and maternal outcomes. Infants are primarily at risk of stillbirth, preterm birth, low birth weight, and small-for-gestational age birth.

Eating Disorders During Gestation: Implications for Mother's Health, Fetal Outcomes, and Epigenetic Changes

Introduction: Eating disorders (EDs) have increased globally in women of childbearing age, related to the concern for body shape promoted in industrialized countries. Pregnancy may exacerbate a previous ED or conversely may be a chance for improving eating patterns due to the mother's concern for the unborn baby. EDs may impact pregnancy evolution and increase the risk of adverse outcomes such as miscarriage, preterm delivery, poor fetal growth, or malformations, but the knowledge on this topic is limited. Methods: We performed a systematic review of studies on humans in order to clarify the mechanisms underpinning the adverse pregnancy outcomes in patients with EDs. Results: Although unfavorable fetal development could be multifactorial, maternal malnutrition, altered hormonal pathways, low pre-pregnancy body mass index, and poor gestational weight gain, combined with maternal psychopathology and stress, may impair the evolution of pregnancy. Environmental factors such as malnutrition or substance of abuse may also induce epigenetic changes in the fetal epigenome, which mark lifelong health concerns in offspring. Conclusions: The precocious detection of dysfunctional eating behaviors in the pre-pregnancy period and an early multidisciplinary approach comprised of nutritional support, psychotherapeutic techniques, and the use of psychotropics if necessary, would prevent lifelong morbidity for both mother and fetus. Further prospective studies with large sample sizes are needed in order to design a structured intervention during every stage of pregnancy and in the postpartum period.

Adverse Birth Outcomes Associated with Types of Eating Disorders: A Review

At least 5% of women have an eating disorder (ED) during pregnancy. These EDs affect prepregnancy body mass index (BMI) and weight gain during pregnancy, factors associated with birth complications and adverse neonatal outcomes. This review contributes to the literature by examining several adverse birth outcomes associated with EDs and differentiates between past and present EDs. Of the 18 articles reviewed, EDs were associated with preterm birth in 5/14 (36%) and small-for-gestational-age in 5/8 (63%) studies. Anorexia Nervosa increases the odds of a low birth weight baby, particularly when women enter pregnancy with a low BMI. Binge Eating Disorder is positively associated with having a large-for-gestational-age infant, and Bulimia Nervosa is associated with miscarriage when symptomatic during pregnancy. Having a current ED increases the risk for adverse birth outcomes more than a past ED. Since the aetiology of adverse birth outcomes is multi-factorial, drawing conclusions about causal relationships between EDs and birth outcomes is problematic given the small number of studies reporting these outcomes. Resources should target preconception interventions that put EDs into remission and help women achieve a healthier BMI prior to pregnancy, as these have been consistently shown to improve birth outcomes.

The Impact of Maternal Eating Disorders on Dietary Intake and Eating Patterns during Pregnancy: A Systematic Review

Maternal nutrition in pregnancy has a key influence on optimum fetal health. Eating disorders (EDs) during pregnancy may have detrimental effects on fetal growth and the child’s early development. There is limited knowledge concerning the eating behavior, dietary intake and derived nutritional biomarkers as well as the nutrient supplementation in women with EDs during pregnancy. We performed a systematic review according to the PRISMA statement to synthesize current evidence in this field. Of N = 1203 hits, 13 full-texts were included in the qualitative synthesis. While women with current Binge Eating Disorder (BED) showed higher energy and fat intakes during pregnancy, women with a lifetime Anorexia Nervosa (AN), Bulimia Nervosa (BN) or both (AN + BN) had similar patterns of nutrient intake and dietary supplement use as healthy women. There is evidence, that women with a history of EDs have a sufficient diet quality and are more likely to be vegetarian. Dieting and bingeing improved substantially with pregnancy. The highlighted differences in the consumption of coffee/caffeine and artificially sweetened beverages as well as the elevated prevalence of iron deficiency anemia in women with a past or active ED during pregnancy might have an important impact on fetal development.

Embodied Motherhood: Exploring Body Image in Pregnant and Parenting Youth

STUDY OBJECTIVE

There is a paucity of research on body image in pregnant and parenting youth (PPY). Study objectives were to examine: (1) profiles of PPY regarding body image, depression, and eating behaviors and any effects of age and pregnancy status on results; and (2) PPY perceptions of body image. DESIGN, SETTING, PARTICIPANTS, INTERVENTIONS, AND MAIN OUTCOME MEASURES: Demographic data and scores from measures related to self-esteem, body esteem, eating behaviors, and depression were collected from 101 PPY from 2 urban centers. Two focus group sessions were held to further explore survey findings. Sessions were audio-recorded and transcribed verbatim for analysis.

RESULTS

Participants (mean age, 19.8 years) reported a history of depression (79/101; 78.2%), anxiety (75/101; 74.3%), drug/alcohol abuse (45/101; 44.6%), and eating disorder (32/101; 31.7%). Parenting (nonpregnant; n = 64) participants had lower body esteem (P = .041) and more eating disorder behaviors (P = .026) compared with pregnant (n = 37) participants. A history of depression or eating disorder both independently increased risk for lower body esteem and self-esteem and higher depressive symptoms in pregnant youth. Four dominant themes emerged from qualitative data: (1) adapting to rapidly changing bodies; (2) inter-relationship between body image and mood; (3) added attention and perceptions of pressure to return to prepregnancy body size; and (4) reconciling change and striving to find a new normal.

CONCLUSION

This study highlights the importance of exploring past and current body image, mood, and eating disorder behavior in PPY for risk of current mental health issues. Future research exploring prepregnancy depression, eating disorder, body esteem, and depression in pregnant youth are needed.

Impact of eating disorders on obstetric outcomes in a large clinical sample: A comparison with the HUNT study

OBJECTIVE

Current evidence from clinical studies suggests that having an active eating disorder (ED) during pregnancy is associated with unfavorable obstetric outcomes. However, the role of a lifetime diagnosis of ED is not fully understood. Variations in findings suggest a need for additional studies of maternal ED. This study aims to identify associations between a lifetime ED and obstetric outcomes.

METHOD

Data from a hospital patient register and a population-based study (The HUNT Study) were linked to the Medical Birth Registry in Norway. Register based information of obstetric complications (preeclampsia, preterm birth, perinatal deaths, small for gestational age (SGA), large for gestational age (LGA), Caesarean sections, and 5-min Apgar score) were acquired for 532 births of women with ED and 43,657 births of non-ED women. Multivariable regression in generalized estimating equations was used to account for clusters within women as they contributed multiple births to the dataset.

RESULTS

After adjusting for parity, maternal age, marital status, and year of delivery, lifetime history of anorexia nervosa was associated with increased odds of having offspring who were SGA (Odds ratio (OR) 2.7, 95% Confidence Interval (CI) 1.4-5.2). Women with a lifetime history of bulimia nervosa had higher odds of having a Caesarian section (OR 1.7 95% CI 1.1-2.5). Women with EDNOS/sub-threshold ED had a higher likelihood of having a low Apgar score at 5 min (OR 3.1, 95% CI 1.1-8.8).

CONCLUSION

Our study corroborates available evidence on the associations between maternal ED and adverse obstetric outcomes.

Adolescent pregnancy and eating disorders: a minireview and case report

BACKGROUND

Despite the fact that eating disorders (EDs) during pregnancy and early child bearing can both individually increase risk to mother and child, there is a paucity of research exploring pregnancy in adolescence and concomitant EDs.

CASE

We report the case of a 16-year-old female with atypical anorexia nervosa, who experiences a remission of her ED behavior during pregnancy, followed by a severe relapse in the post-partum period.

CONCLUSION

In this case, pregnancy functioned as a motivator for remission in our patient with concomitant ED. Further research is needed to identify risks of EDs in adolescent pregnancy, to explore the trajectory of pre-existing EDs during pregnancy and to identify effective interventions for prolonging remission into the post-partum period.

Maternal eating disorders and perinatal outcomes: A three-generation study in the Norwegian Mother and Child Cohort Study

Previous studies of the relationship between maternal eating disorders and adverse perinatal outcomes have failed to control for familial transmission of perinatal phenotypes, which may confound the reported association. In a unique design afforded by the Norwegian Mother and Child Cohort Study and Medical Birth Registry of Norway, we linked three generations through birth register records and maternal-reported survey data to investigate whether maternal eating disorders increase risk after parsing out the contribution of familial transmission of perinatal phenotypes. The samples were 70,881 pregnancies in grandmother-mother-child triads for analyses concerning eating disorder exposure during pregnancy and 52,348 for analyses concerning lifetime maternal eating disorder exposure. As hypothesized, eating disorders predicted a higher incidence of perinatal complications even after adjusting for grandmaternal perinatal phenotypes. For example, anorexia nervosa immediately prior to pregnancy was associated with smaller birth length (relative risk = 1.62; 95% CI [1.20, 2.14]), bulimia nervosa with induced labor (relative risk = 1.21; 95% CI [1.07, 1.36]), and binge-eating disorder with several delivery complications, larger birth length (relative risk = 1.25; 95% CI [1.17, 1.34]), and large-for-gestational-age (relative risk = 1.04; 95% CI [1.01, 1.06]). Maternal pregravid body mass index and gestational weight mediated most associations. Our results support that exposure to eating disorders increases the risk for negative health outcomes in pregnant women and their babies. (PsycINFO Database Record

Pregnancy, obstetric, and perinatal health outcomes in eating disorders

OBJECTIVE

The purpose of this study was to assess pregnancy, obstetric, and perinatal health outcomes and complications in women with lifetime eating disorders.

STUDY DESIGN

Female patients (n = 2257) who were treated at the Eating Disorder Clinic of Helsinki University Central Hospital from 1995-2010 were compared with unexposed women from the population (n = 9028). Register-based information on pregnancy, obstetric, and perinatal health outcomes and complications were acquired for all singleton births during the follow-up period among women with broad anorexia nervosa (AN; n = 302 births), broad bulimia nervosa (BN; n = 724), binge eating disorder (BED; n = 52), and unexposed women (n = 6319).

RESULTS

Women with AN and BN gave birth to babies with lower birthweight compared with unexposed women, but the opposite was observed in women with BED. Maternal AN was related to anemia, slow fetal growth, premature contractions, short duration of the first stage of labor, very premature birth, small for gestational age, low birthweight, and perinatal death. Increased odds of premature contractions, resuscitation of the neonate, and very low Apgar score at 1 minute were observed in mothers with BN. BED was associated positively with maternal hypertension, long duration of the first and second stage of labor, and birth of large-for-gestational-age infants.

CONCLUSION

Eating disorders appear to be associated with several adverse perinatal outcomes, particularly in offspring. We recommend close monitoring of pregnant women with either a past or current eating disorder. Attention should be paid to children who are born to these mothers.

Minireview: Metabolism of female reproduction: regulatory mechanisms and clinical implications

Female fertility is highly dependent on successful regulation of energy metabolism. Central processes in the hypothalamus monitor the metabolic state of the organism and, together with metabolic hormones, drive the peripheral availability of energy for cellular functions. In the ovary, the oocyte and neighboring somatic cells of the follicle work in unison to achieve successful metabolism of carbohydrates, amino acids, and lipids. Metabolic disturbances such as anorexia nervosa, obesity, and diabetes mellitus have clinically important consequences on human reproduction. In this article, we review the metabolic determinants of female reproduction and their role in infertility.

Low birth weight in the offspring of women with anorexia nervosa

A growing body of literature has investigated the association between maternal anorexia nervosa and pregnancy outcomes. Infant low birth weight is associated with a number of neurodevelopmental and physical sequelae; however, consistent results on its association with maternal anorexia nervosa are scant. Therefore, a systematic review and meta-analysis of the existing literature were undertaken. PubMed, Embase, and PsychInfo were searched for studies comparing the mean birth weight of babies delivered by mothers with (a history of) anorexia nervosa against those of healthy mothers. Studies were excluded from the meta-analysis if not presenting data from an unexposed comparison group and if using multiple eating disorders as exposure without presenting individual results. Fourteen studies were included in the systematic review and 9 in the meta-analysis, undertaken between 1999 and 2012 in Denmark, the Netherlands, New Zealand, Norway, Sweden, and the United Kingdom. Birth weights were standardized by dividing the difference in mean birth weight by the pooled standard deviation (equivalent to Cohen's d). Results showed a standardized mean difference of -0.19 kg (95% confidence interval: -0.25, -0.15; P = 0.01) in the birth weight of children of mothers with anorexia nervosa, and some bias in favor of papers presenting lower birth weight results for exposed mothers was detected. However, the small power of the analysis due to the small number of available studies and, thus, chance could partially account for this result. Our results confirm that maternal anorexia nervosa predicts lower birth weight and, despite some limitations, they have important clinical implications for prevention of adverse child outcomes.