Sonographic measurement of the fetal thymus: Relationship with maternal obesity.

BACKGROUND

The purpose of this study was to evaluate the influence of maternal obesity on the size of the fetal thymus.

METHODS

The study population consisted of 138 pregnant women who were divided into two groups based on their body mass index (BMI): Normal-weight group (n = 97; BMI: 18-25 kg/m2 ) and obese group (n = 41; BMI: ≥ 30 kg/m2 ). All participants underwent routine second-trimester prenatal ultrasound (US) screening at 20-25 weeks of gestation. Differences in US measurement of fetal thymus, fetal anthropometric measurements, subcutaneous adipose tissue thickness, fetal weight, gestational age, white blood cell count, and C-reactive protein (CRP) values between groups were compared.

RESULTS

The mean thymus size was 18.7 ± 2.9 mm for normal-weight group, and 21.6 ± 3.7 mm for the obese group (p < 0.001). CRP values were also significantly different between groups (6.8 ± 4.4 mg/dl for normal-weight group, 14.8 ± 1.8 mg/dl for obese group, p < 0.001).

CONCLUSIONS

Fetal thymus size was increased in obese women, and this increase may indicate immunologic abnormalities in fetuses. However, future large-scale studies are necessary to support this association. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:277-281, 2017.