Changing trends of birth weight with maternal age: a cross-sectional study in Xi’an city of Northwestern China

Abstract

Background Most studies have shown that maternal age is associated with birth weight. However, the specific relationship between each additional year of maternal age and birth weight remains unclear. The study aimed to analyze the specific association between maternal age and birth weight. Methods Raw data for all live births from 2015 to 2018 were obtained from the Medical Birth Registry of Xi’an, China. A total of 490,143 mother-child pairs with full-term singleton live births and the maternal age ranging from 20 to 40 years old were included in our study. Birth weight, gestational age, neonatal birth date, maternal birth date, residence and ethnicity were collected. Generalized additive model and two-piece wise linear regression model were used to analyze the specific relationships between maternal age and birth weight, risk of low birth weight, and risk of macrosomia. Results The relationships between maternal age and birth weight, risk of low birth weight, and risk of macrosomia were nonlinear. Birth weight increased 16.204 g per year when maternal age was less than 24 years old (95%CI: 14.323, 18.086), and increased 12.051 g per year when maternal age ranged from 24 to 34 years old (95%CI: 11.609, 12.493), then decreased 0.824 g per year (95% CI: -3.112, 1.464). The risk of low birth weight decreased with the increase of maternal age until 36 years old (OR = 0.917, 95%CI: 0.903, 0.932 when maternal age was younger than 27 years old; OR = 0.965, 95%CI: 0.955, 0.976 when maternal age ranged from 27 to 36 years old), then increased when maternal age was older than 36 years old (OR = 1.133, 95%CI: 1.026, 1.250). The risk of macrosomia increased with the increase of maternal age (OR = 1.102, 95%CI: 1.075, 1.129 when maternal age was younger than 24 years old; OR = 1.065, 95%CI: 1.060, 1.071 when maternal age ranged from 24 to 33 years old; OR = 1.029, 95%CI: 1.012, 1.046 when maternal age was older than 33 years old). Conclusions For women of childbearing age (20–40 years old), the threshold of maternal age on low birth weight was 36 years old, and the risk of macrosomia increased with the increase of maternal age.

Second-Hand Smoke Exposure inside the House and Adverse Birth Outcomes in Indonesia: Evidence from Demographic and Health Survey 2017

“…There were 58% of women in our sample had daily exposure; these women were younger maternal age (the proportion of women maternal age 15-24 was 12.7% vs 19.9% with non-daily vs daily (or 1.6 times)), which may drive the higher birth rates among daily. One study in China showed that birth weight increased 16.204 g per year when maternal age was less than 24 years old, and increased 12.051 g per year when maternal age ranged from 24 to 34 years old, then decreased 0.824 g per year from 34+ years (Wang et al, 2020). In our study, although it has been controlled for maternal age in regression, it still shows U-shaped for daily, so that the potential explanation could be maternal age.…”

Selfish centromeres and the wastefulness of human reproduction

“…In humans, we then also expect the extent of reproductive compensation to vary with maternal age as birth weight of the baby varies with age, with a peak at about the same maternal age as the inflection point of increased aneuploidy rates, i.e., 35 to 36 [ 68 ]. Assuming higher birth weight (within normal bounds) usually implies higher fitness, the profile of birth weights with age is such that there could be stronger selection for death by selfish aneuploidy in older mothers.…”

Kajian Kejadian Berat Badan Lahir Rendah di Indonesia: Analisis Data Survei Demografi dan Kesehatan Indonesia tahun 2017

“…Ibu yang berusia di bawah 20 tahun teridentifikasi melahirkan bayi dengan rata-rata berat badan terendah jika dibandingkan dengan ibu berusia di atas 20 tahun yang juga melahirkan bayi dengan berat badan < 2.500 gram. Hasil penelitian ini sejalan dengan penelitian yang dilakukan di China, Pakistan dan Yordania (4)(5)(6). Tidak terdapat perbedaan rerata BBLR antar kelompok usia ibu yang signifikan secara statistik.…”

“…Setiap penambahan atau pengurangan satu tahun usia ibu akan meningkatkan atau menurunkan 4,3 gram berat bayi yang dilahirkan (5). Namun, penelitian sebelumnya secara spesifik menunjukkan adanya peningkatan risiko BBLR pada kelompok usia ibu tertentu yang digambarkan dengan kurva U (4,6). Risiko BBLR teridentifikasi lebih tinggi dialami oleh ibu berusia <20 tahun dan >34 tahun.…”

“…Peningkatan risiko BBLR yang dimiliki oleh ibu pada kelompok usia tertentu berkaitan dengan kondisi biologis sistem reproduksi. Pada kelompok usia ibu < 20 tahun, kematangan sistem reproduksi dinilai belum/ kurang memadai untuk menerima kehamilan sementara pada kelompok usia ibu >34 tahun, penurunan kondisi kesehatan ibu dan kualitas sel telur dapat meningkatkan kerentanan ibu terhadap preeklamsia dan hipertensi terkait kehamilan yang dapat mempengaruhi proses tumbuh kembang janin sehingga komplikasi atau kelahiran prematur yang mengakibatkan BBLR (4,7,8).…”