Waist to hip circumference ratio as a significant predictor of preeclampsia, irrespective of overall adiposity

Age at Menarche Mediating Visceral Adipose Tissue's Influence on Pre-eclampsia: A Mendelian Randomization Study

CONTEXT

The association between visceral adipose tissue (VAT) and pre-eclampsia (PE) shows inconsistent results and the underlying mediator remains unknown.

OBJECTIVE

We aimed to explore the causal effect of VAT on PE risks and the mediation role of age at menarche (AAM) in explaining this relationship.

METHODS

Summary data for PE were obtained from the FinnGen genome-wide association study (3556 cases and 114 735 controls). For exposure data, 70 genetic variants associated with the predicted VAT in 161 149 European women from UK Biobank were used as instrumental variables. Inverse variance weighted and multiple sensitivity analyses were applied. We also conducted multivariable Mendelian randomization (MR) analyses to test the association between VAT-associated single-nucleotide variations and PE. Next, mediation analyses were performed to study whether the association between VAT and PE was mediated via AAM.

RESULTS

In univariable MR analysis, higher volume of VAT was associated with the advancement of AAM and increased PE risk (beta = -0.33; 95% CI, -0.49 to -0.16 for AAM; odds ratio 1.65, 95% CI, 1.23 to 2.20 for PE). After adjusting for waist circumference, waist to hip ratio, and hip circumference, the multivariable MR results presented the consistent positive causality of VAT on PE. Two-step MR analysis proved an estimated 14.3% of the positive effect of VAT on PE was mediated by AAM.

CONCLUSION

Our findings provided evidence of the causal relationship between VAT and PE and proved VAT could accelerate AAM and then contribute to the risk of incident PE.

Evolutionary Theories and Men's Preferences for Women's Waist-to-Hip Ratio: Which Hypotheses Remain? A Systematic Review

Over the last 25 years, a large amount of research has been dedicated to identifying men's preferences for women's physical features, and the evolutionary benefits associated with such preferences. Today, this area of research generates substantial controversy and criticism. I argue that part of the crisis is due to inaccuracies in the evolutionary hypotheses used in the field. For this review, I focus on the extensive literature regarding men's adaptive preferences for women's waist-to-hip ratio (WHR), which has become a classic example of the just-so storytelling contributing to the general mistrust toward evolutionary explanations of human behavior. The issues in this literature originate in the vagueness and incompleteness of the theorizing of the evolutionary mechanisms leading to mate preferences. Authors seem to have rushed into testing and debating the effects of WHR on women's attractiveness under various conditions and using different stimuli, without first establishing (a) clear definitions of the central evolution concepts (e.g., female mate value is often reduced to an imprecise concept of "health-and-fertility"), and (b) a complete overview of the distinct evolutionary paths potentially at work (e.g., focusing on fecundability while omitting descendants' quality). Unsound theoretical foundations will lead to imprecise predictions which cannot properly be tested, thus ultimately resulting in the premature rejection of an evolutionary explanation to human mate preferences. This paper provides the first comprehensive review of the existing hypotheses on why men's preferences for a certain WHR in women might be adaptive, as well as an analysis of the theoretical credibility of these hypotheses. By dissecting the evolutionary reasoning behind each hypothesis, I show which hypotheses are plausible and which are unfit to account for men's preferences for female WHR. Moreover, the most cited hypotheses (e.g., WHR as a cue of health or fecundity) are found to not necessarily be the ones with the strongest theoretical support, and some promising hypotheses (e.g., WHR as a cue of parity or current pregnancy) have seemingly been mostly overlooked. Finally, I suggest some directions for future studies on human mate choice, to move this evolutionary psychology literature toward a stronger theoretical foundation.

Waist-to-hip ratio versus body mass index as predictors of fitness in women

The claim that men prefer women with low waist-to-hip ratios (WHR) has been vigorously disputed. We examine self-report data from 359 primiparous Polish women (with normal singleton births and healthy infants) and show that WHR correlates with at least one component of a woman's biological fitness (her first child's birth weight, a variable that significantly affects infant survival rates). However, a woman's Body Mass Index (BMI) is a better predictor of her child's neonatal weight in small-bodied women (<54 kg). The failure to find a preference for low WHR in some traditional populations may thus be a consequence of the fact that, even in western populations, body mass is a better predictor of fitness in those cases characterized by low maternal body weight.

Follistatin-like 3 across gestation in preeclampsia and uncomplicated pregnancies among lean and obese women

The purpose of this study was to examine circulating maternal follistatin-like 3 (FSTL-3) by gestational age and obesity in pregnancy and preeclampsia. FSTL-3 was quantified in maternal plasma collected in each trimester from prepregnancy body mass index-determined groups: 15 lean and 24 obese controls and 20 obese women who developed preeclampsia. Repeated measures mixed models and logistic regression were conducted (P ≤ .05). FSTL-3 was not related to maternal adiposity. FSTL-3 changed across pregnancy in lean controls and obese preeclampsia but not in obese controls. FSTL-3 was higher in preeclampsia in the second trimester compared to lean controls and in the third trimester compared to both control groups. Elevated FSTL-3 at mid-gestation was associated with an increased odds of preeclampsia (odds ratio 3.15; 95% confidence interval 1.19-8.36; P = .02). Elevated FSTL-3 concentrations were attributable to preeclampsia and were associated with increased likelihood of later developing preeclampsia, suggesting further study as a biomarker prior to clinically evident disease.

Evaluation of some anthropometric indices for the diagnosis of obesity in pregnancy in Nigeria: a cross-sectional study

BACKGROUND

Obesity in pregnancy is a global health problem which is associated with poor pregnancy outcomes. The use of weight and height, measured at about ten weeks of gestation, to produce pre-gestational body mass index is recommended for the diagnoses of the condition but limitations abound in under resourced settings.

OBJECTIVES

To measure anthropometric indices such as mid upper arm circumference, calf circumference, waist circumference and waist to hip ratio, for identification of obesity in pregnancy.

METHODS

Anthropometric measurements were carried out on cohorts of pregnant women from 4 hospitals in Enugu, South-eastern Nigeria.

RESULTS

There were no significant difference in the mean mid upper arm circumference (MUAC) and calf circumference (CC) across the trimester groups. The mean values of waist circumferences, hip circumference and waist to hip ratios changed significantly across the trimesters. The 75(th) percentile of MUAC (33 cm) and CC (39 cm) in all trimesters, had sensitivity and specificity of more than 70% for identifying obesity in pregnancy.

CONCLUSION

MUAC and CC values of 33cm and 39cm respectively might be reliable cut off points for diagnoses of obesity throughout pregnancy in Enugu, Nigeria.

Obstetrical sonography in obese women: a review

Obstetric sonographic imaging in pregnant women is adversely affected by obesity with a negative impact on the detection rate of congenital anomalies. This review aims to analyze relevant data regarding this issue and to discuss clinical and technical problems associated with sonographic examination of obese pregnant women.

Systematic review: Accuracy of body mass index in predicting pre-eclampsia: bivariate meta-analysis

OBJECTIVE

The objective of this study was to determine the accuracy of body mass index (BMI) (pre-pregnancy or at booking) in predicting pre-eclampsia and to explore its potential for clinical application.

DESIGN

Systematic review and bivariate meta-analysis.

SETTING

Medline, Embase, Cochrane Library, MEDION, manual searching of reference lists of review articles and eligible primary articles, and contact with experts.

POPULATION

Pregnant women at any level of risk in any healthcare setting.

METHODS

Reviewers independently selected studies and extracted data on study characteristics, quality, and accuracy. No language restrictions.

MAIN OUTCOME MEASURES

Pooled sensitivities and specificities (95% CI), a summary receiver operating characteristic curve, and corresponding likelihood ratios (LRs). The potential value of BMI was assessed by combining its predictive capacity for different prevalences of pre-eclampsia and the therapeutic effectiveness (relative risk 0.90) of aspirin.

RESULTS

A total of 36 studies, testing 1,699,073 pregnant women (60,584 women with pre-eclampsia), met the selection criteria. The median incidence of pre-eclampsia was 3.9% (interquartile range 1.4-6.8). The area under the curve was 0.64 with 93% of heterogeneity explained by threshold differences. Pooled estimates (95% CI) for all studies with a BMI > or = 25 were 47% (33-61) for sensitivity and 73% (64-83) for specificity; and 21% (12-31) and 92% (89-95) for a BMI > or = 35. Corresponding LRs (95% CI) were 1.7 (0.3-11.9) for BMI > or = 25 and 0.73 (0.22-2.45) for BMI < 25, and 2.7 (1.0-7.3) for BMI > or = 35 and 0.86 (0.68-1.07) for BMI < 35. The number needed to treat with aspirin to prevent one case of pre-eclampsia ranges from 714 (no testing, low-risk women) to 37 (BMI > or = 35, high-risk women).

CONCLUSIONS

BMI appears to be a fairly weak predictor for pre-eclampsia. Although BMI is virtually free of cost, noninvasive, and ubiquitously available, its usefulness as a stand-alone test for risk stratification must await formal cost-utility analysis. The findings of this review may serve as input for such analyses.

Ultrasound evaluation of visceral fat and metabolic risk factors during early pregnancy

OBJECTIVE

The objective was to study the relationships between ultrasound estimated visceral fat and metabolic risk factors during early pregnancy.

RESEARCH METHODS AND PROCEDURES

Thirty consecutive healthy pregnant women at 11 to 14 weeks of gestation were studied. Maximum subcutaneous fat thickness (SFT) and visceral fat thickness (VFT) were successfully measured by ultrasound. Fasting plasma glucose, insulin, triglycerides, total cholesterol, high-density lipoprotein cholesterol (HDL-C), and blood pressure were measured. Insulin resistance was calculated by using the homeostasis model assessment (HOMA).

RESULTS

VFT significantly correlated with diastolic blood pressure (r = 0.37, p = 0.04), glycemia (r = 0.37, p = 0.04), insulinemia (r = 0.59, p = 0.001) insulin sensitivity (HOMA; r = 0.59, p = 0.001), triglycerides (r = 0.58, p = 0.03), HDL-C (r = -0.39, p = 0.03), and total cholesterol/HDL-C ratio (p = 0.002), whereas SFT was significantly correlated with only diastolic blood pressure (p = 0.03). VFT better significantly correlated with the metabolic risk factors than pre-gestational BMI [r = 0.39, p = 0.03 for insulinemia, r = 0.42, p = 0.02 for insulin sensitivity (HOMA), and r = 0.49, p = 0.01 for triglycerides and not significant for the rest].

DISCUSSION

Visceral fat thickness can be easily measured by ultrasound at early pregnancy and correlates better than BMI with metabolic risk factors.

Determination of Maternal Body Composition in Pregnancy and Its Relevance to Perinatal Outcomes

Three models and 10 specific methods for determining maternal body composition are discussed and their perinatal relevance reviewed. English language publications (1950 to January 2004) were searched electronically and by hand. Search terms included "body composition," "human," " pregnancy," "obesity," "adiposity," "regional," "2-, 3-, 4-component," "truncal," "peripheral," "central," "visceral" along with specific techniques and outcomes listed subsequently. Three models of body composition are described: 2-component being fat and fat-free mass; 3-component being fat, water, and protein; and 4-component being fat, water, protein, and osseous mineral. Ten techniques of body composition assessment are described: 1) anthropometric techniques including skinfold thicknesses and waist-hip ratio; 2) total body water (isotopically labeled); 3) hydrodensitometry (underwater weighing); 4) air-displacement plethysmography; 5) bio-impedance analysis (BIA); 6) total body potassium (TBK); 7) dual-energy x-ray absorptiometry (DEXA); 8) computed tomography (CT); 9) magnetic resonance imaging (MRI); and 10) ultrasound (USS). Most methods estimate total adiposity. Regional fat distribution-central (truncal) compared with peripheral (limb) or visceral compared with subcutaneous-is important because of regional variation in adipocyte metabolism. Skinfolds, DEXA, CT, MRI, or USS can distinguish central from peripheral fat. CT, MRI, or USS can further subdivide central fat into visceral and subcutaneous. Perinatal outcomes examined in relation to body composition include pregnancy duration, birth weight, congenital anomalies, gestational diabetes, gestational hypertension, and the fetal origins of adult disease. A few studies suggest that central compared with peripheral fat correlates better with birth weight, gestational carbohydrate intolerance, and hypertension. Means of accurately assessing maternal body composition remain cumbersome and impractical, but may more accurately predict perinatal outcomes than traditional assessments such as maternal weight.