Does the Summer Season Affect the Amniotic Fluid Volume during Pregnancy?

Ah-Young Choi,Myoung-Hwan Kim,Yong-Soo Seo,Seung-Woo Yang,Han-Sung Hwang,Jun-Yi Lee,In-Sook Sohn,Han-Sung Kwon

doi:10.3390/ijerph18189483

Abstract

Amniotic fluid is crucial for the well-being of the fetus. Recent studies suggest that dehydration in a pregnant woman leads to oligohydramnios. We assessed the variation in the amniotic fluid index (AFI) during the summer and non-summer seasons and evaluated neonatal outcomes. We retrospectively reviewed electrical medical records of pregnant women who visited the Konkuk University Medical Center for antenatal care, between July 2005 and July 2019. A total of 19,724 cases from 6438 singleton pregnant women were included after excluding unsuitable cases. All AFI values were classified as 2nd and 3rd trimester values. Additionally, borderline oligohydramnios (AFI, 5–8) and normal AFI (AFI, 8–24) were assessed according to the seasons. The average AFI between the summer and non-summer season was statistically different only in the 3rd trimester; but the results were not clinically significant. In the 3rd trimester, the summer season influenced the increased incidence of borderline oligohydramnios. The borderline oligohydramnios group showed an increased small-for-gestational-age (SGA) rate and NICU admission rate. In the summer season, the incidence of borderline oligohydramnios was seen to increase. This result would be significant for both physicians and pregnant women.

Highlights

Published: 8 September 2021The amniotic fluid was previously considered nonfunctional; it is well known that the amniotic fluid is crucial for the lung maturation, gastrointestinal tract development, and neuromuscular development of the fetus
We excluded the data of pregnant women in the 1st trimester pregnancy, and with oligohydramnios (AFI, 24), premature rupture of membrane (PROM), diabetes mellitus (DM), gestational diabetes mellitus (GDM), pre-eclampsia, multifetal gestation, and fetal anomaly that causes abnormal amniotic fluid volume
The average amniotic fluid index (AFI) increased throughout the 2nd trimester and slightly decreased in the 3rd trimester [1,29]

Summary

Introduction

Published: 8 September 2021The amniotic fluid was previously considered nonfunctional; it is well known that the amniotic fluid is crucial for the lung maturation, gastrointestinal tract development, and neuromuscular development of the fetus. The amniotic fluid volume increases from around 30 mL at 10 weeks of gestation to 800 mL during the mid-third trimester [1,2]. The amniotic fluid volume is regulated by four main pathways: (i) fetal urination, (ii) intramembranous osmolality difference, (iii) respiratory tract, and (iv) fetal swallowing. An abnormality in the amniotic fluid volume may result from fetal or placental pathology [3]. The amniotic fluid index (AFI) has been an integral component of fetal assessment during an antepartum ultrasound examination for more than 20 years [1,4,5]. A decrease in amniotic fluid, oligohydramnios, is typically defined as an AFI of less than 5 cm, which represents a value below the first percentile [7].

Methods

Results

Discussion

Conclusion