The relationship between placental thickness and gestational age in pregnant women: A cross-sectional study

Estimating gestational age (GA) is of utmost importance to assess the condition of the fetus. Incorporating placental thickness and fetal biometrics in estimating GA may improve the accuracy of fetal age estimation. The aim of this study was to examine the relationship between placental thickness and GA in pregnant women referred to Al-Zahra Hospital's prenatal and emergency clinic in Rasht, Iran.

This cross-sectional study was conducted on pregnant women referred to Al-Zahra Clinic for prenatal care over a 6-month period. After obtaining informed consent, data were collected on the date of the first day of the last safe menstruation, average body mass index, and medical and surgical history. Placental thickness was estimated using ultrasound and various clinical information was recorded. The data were then analyzed using Pearson correlation analysis in SPSS software version 21.

The results showed a significant correlation between GA and placental thickness (p < 0.0001, r = 0.729). Placental thickness increased with increasing GA. There was also a significant relationship between placental thickness and placental location (p = 0.009, r = 0.14). In the posterior position, placental thickness increased by 14% or 0.14. The placental thickness in the posterior position (29.49 ± 0.75) was greater than the anterior position (26.94 ± 10.72).

The findings of this study suggest that there is a significant increase in placental thickness with increasing GA during the first and second trimesters. Additionally, placental thickness significantly increased in the posterior placental position, as well as in women with high BMI. Therefore, it is recommended that measuring placental thickness should be routine during obstetric ultrasounds.