Low birth weight and its associated biopsychosocial factors over a 19-year period: findings from a national cohort study

Maternal Hypertension Aggravates Vascular Dysfunction After Injury in Male Adult Offspring Through Transgenerational Transmission of N6-Methyladenosine

BACKGROUND

Whether maternal hypertension contributes to the enhanced susceptibility to vascular remodeling in adult offspring through epigenetic mechanisms remains unclear. We aimed to address this gap in the literature using a transgenerational mouse model.

METHODS

Gestational hypertension was induced in pregnant mice using chronic angiotensin II infusion. Blood pressure was monitored using the tail-cuff method. Two months post-delivery, an N6-methyladenosine epitranscriptomic microarray analysis was performed on the carotid arteries of second-generation mice. A unilateral carotid artery injury model was used to study the postinjury vascular response in vivo. Furthermore, carotid ultrasonography, immunohistochemistry, and molecular biological parameters were assessed in adult offspring.

RESULTS

Exposure to maternal hypertension decreased the birth weight of live pups and increased the fetal death rate. Compared with normal offspring, adult offspring with hypertension had wire-induced injury that led to greater vascular remodeling, which was associated with aggravated inflammation imbalance, fibrosis, and oxidative stress. In addition, aberrant N6-methyladenosine methylation, increased N6-methyladenosine levels, and increased METTL3 (methyltransferase-like 3) expression were detected in the vessels of offspring with hypertension. Maternal METTL3 deficiency increased the birth weight of live pups with hypertension, improved vascular dysfunction, and alleviated vascular inflammation in adult offspring with hypertension after injury.

CONCLUSIONS

Maternal hypertension can induce transgenerational transmission of enhanced susceptibility to vascular remodeling, and the possible underlying mechanism is associated with altered METTL3-mediated N6-methyladenosine methylation. Therefore, this study reveals the role of epigenetic effects across generations and provides new insights into vascular remodeling causes.

Being a First Nations baby is not independently associated with low birthweight in a large metropolitan health service

AIM

To examine low birth weight (LBW) in First Nations babies born in a large metropolitan health service in Queensland, Australia.

MATERIALS AND METHODS

A retrospective population-based study using routinely collected data from administrative data sources. All singleton births in metropolitan health services, Queensland, Australia of ≥20 weeks gestation or at least 400 g birthweight and had information on First Nations status and born between 2019 and 2021 were included. The study measured birthweight and birthweight z-score, and also identified the predictors of LBW. Multivariate regression models were adjusted by demographic, socioeconomic and perinatal factors.

RESULTS

First Nations babies had higher rates of LBW (11.4% vs 6.9%, P < 0.001), with higher rates of preterm birth (13.9% vs 8.8%, P < 0.001). In all babies, the most important factors contributing to LBW were: maternal smoking after 20 weeks of gestation; maternal pre-pregnancy underweight (body mass index <18.5 kg/m2); nulliparity; socioeconomic disadvantage; geographical remoteness; less frequent antenatal care; history of cannabis use; pre-existing cardiovascular disease; pre-eclampsia; antepartum haemorrhage; and birth outcomes including prematurity and female baby. After adjusting for all contributing factors, no difference in odds of LBW was observed between First Nations and non-First Nation babies.

CONCLUSIONS

First Nations status was not an independent factor influencing LBW in this cohort, after adjustment for identifiable factors. The disparity in LBW relates to modifiable risk factors, socioeconomic disadvantage, and prematurity. Upscaling culturally safe maternity care, focusing on modifiable risk factors is required to address LBW in Australian women.

The impact of phenylalanine levels during pregnancy on birth weight and later development in children born to women with phenylketonuria

Strict metabolic control with dietary treatment during pregnancy is essential for women with phenylketonuria (PKU), as elevated levels of phenylalanine (Phe) are toxic to the developing fetus. Maternal delay in achievement of the recommended Phe level during pregnancy is associated with delayed development of the child. However, the extent to which risk is changed by later or less stringently performed dietary treatment is unclear. The aim of this study was to investigate the impact of Phe levels and time of initiation of a Phe-restricted diet in pregnant women with PKU on birth weight, head circumference and later development of their children. Birth data were obtained from the medical records of women with PKU giving birth in the period 1980-2020. Later development was investigated by interviewing the mothers about their children's development and health. We included 79 children of 41 women with PKU. The women showed good adherence with the diet and had mean blood Phe levels within target range (248 ± 62 μmol/L). The children's development was not affected by fluctuations in the women's Phe levels, that occurred especially in first trimester. Despite maternal Phe levels being within target range, 19 children (26.8%) had low birth weight below 10th percentile. This study indicates that with dietary treatment, the children are born with the same prospect for normal development and health as children born to non-PKU mothers. This is despite maternal fluctuations in the Phe levels during first trimester.

Prenatal Exposure to Favorable Social and Environmental Neighborhood Conditions Is Associated with Healthy Pregnancy and Infant Outcomes

Neighborhood and individual level risks commonly co-occur for pregnant women and may cumulatively contribute to birth outcomes. Moreover, the relationship between favorable social and environmental neighborhood conditions and perinatal outcomes has been understudied. This study considered the accumulated impact of prenatal exposure to positive neighborhood social, environmental, and educational conditions in relation to maternal health during pregnancy and birth size outcomes. In a prospective study of a multi-ethnic and socioeconomically diverse cohort (n = 239) of pregnant women and their infants, neighborhoods were characterized by the Child Opportunity Index (COI), a census-tract composite indicator representing favorable social, environmental, and educational community conditions. Adjusted generalized estimating equations showed that favorable neighborhood conditions promoted the growth of longer and heavier infant bodies, and reduced the risk of intrauterine growth restriction. The associations were stronger for female versus male infants, though not significantly different. Moreover, COI was associated with better maternal mental health and diet during pregnancy; diet significantly mediated the association between COI and birth size outcomes. This study underscores the importance of considering the accumulated benefit of neighborhood assets for maternal and infant health. Interventions that capitalizes on the full range of contextual assets in which mothers live may promote pregnancy health and fetal growth.