Association between the ratio of placental weight to birthweight and the risk of neurodevelopmental delay in 3-year-Olds: The Japan environment and Children's study

• Published in: Placenta (Eastbourne) 2022-10, Vol.128, p.49-56
• Main Authors: Mitsuda, Naomi, Eitoku, Masamitsu, Yamasaki, Keiko, J-P, Naw Awn, Fujieda, Mikiya, Suganuma, Narufumi, Kamijima, Michihiro, Yamazaki, Shin, Ohya, Yukihiro, Kishi, Reiko, Yaegashi, Nobuo, Hashimoto, Koichi, Mori, Chisato, Ito, Shuichi, Yamagata, Zentaro, Inadera, Hidekuni, Nakayama, Takeo, Iso, Hiroyasu, Shima, Masayuki, Nakamura, Hiroshige, Kusuhara, Koichi, Katoh, Takahiko
• Format: Article
• Language: English
• ISSN: 0143-4004; 1532-3102
• DOI: 10.1016/j.placenta.2022.08.007

The ratio of placental weight to birthweight (PW/BW ratio) is well known as a simple indicator of the prenatal intrauterine environment and placental functioning. We assessed the impact of PW/BW ratio on the risk of neurodevelopmental delay in 3-year-olds. We used data of 71 205 mother–child pairs enrolled in the Japan Environment and Children's Study. Low PW/BW ratio was defined as a PW/BW ratio below the 10th percentile of the study population, high PW/BW ratio was defined as above the 90th percentile, and normal PW/BW ratio was defined as between the low and high PW/BW ratio. Neurodevelopment was assessed using the Japanese translation of the Ages and Stages Questionnaires, third edition. Associations between PW/BW ratio and risk of developmental delay were examined using multivariable models. Compared with boys in the normal PW/BW group, boys in the high PW/BW group had higher risk for developmental delays in all domains except fine motor skills (communication: adjusted risk ratio [aRR], 1.17; 95% confidence interval [CI], 1.04–1.33; gross motor skills: aRR, 1.28; 95% CI, 1.13–1.46; problem solving: aRR, 1.20; 95% CI, 1.09–1.31; personal–social: aRR, 1.26; 95% CI, 1.10–1.43), and boys in the low PW/BW group also had higher risk for developmental delays in some domains. For girls, there was almost no association between PW/BW ratio and developmental delay. An unbalanced PW/BW ratio, especially high PW/BW ratio, might indicate intrauterine suboptimality, which affects child neurodevelopment in a sex-specific manner. •Placental weight/birthweight (PW/BW) ratio is known to reflect placental function.•Association between PW/BW ratio and risk of neurodevelopmental delay was examined.•High PW/BW ratio was associated with increased risk of developmental delay in boys.•Unbalanced PW/BW ratio may indicate intrauterine suboptimality.