Preterm birth (defined as birth prior to 37 weeks of gestation) and low birthweight (defined as birthweight <2500g) remain the leading cause of morbidity and mortality in neonates worldwide.  

In South Africa, the neonatal mortality rate in 2017 was reported as 12 per 1000 live births. A 2020 study in South Africa (KwaZulu-Natal) found that 16.4 and 13.5% of babies born were preterm and had a low birthweight, respectively. 

In comparison to term infants, preterm neonates are more susceptible to short and long-term neurocognitive and motor deficits, as well as malnutrition, chronic illnesses, and early death. 

Low birthweight babies are at a higher risk of death and illness shortly after birth and non-communicable disease in the life course. Low birthweight infants are 20 times more likely to develop complications and die in comparison to normal weight babies.  

Low birthweight babies are in the potential risk of cognitive deficits, motor delays, cerebral palsy, and other behaviour and psychological problem.  

Apart from exposure to phthalates in utero, preterm and low birthweight babies are further exposed to these EDCs during their stay in paediatric intensive care units (PICUs). 

Examples of the impact of EDCs on neonates treated in PICUs: 

• Ventilated neonates with high levels of di(2- ethylhexyl) phthalate (DEHP) experienced respiratory degradation associated with progressive radiological infiltrates  

• Neonates in whom a large number of polyvinyl chloride (PVC)-containing medical devices were used for treatment had urinary bisphenol A (BPA) concentrations one order of magnitude higher than the median concentration and almost twice that of the 95th percentile of the general population 

• The use of infusion systems containing DEHP for total parenteral nutrition was linked with a five- to six-fold increase in the risk of cholestasis in neonates. Moreover, the level of cholestasis in neonates was reduced from 50% to 13% in neonates fed through a DEHP-free catheter 

• Premature neonates undergoing treatment were found to have BPA levels 10 times higher than the general population, presumably from BPA leaching from medical devices   

• DEHP leached from endotracheal tubes immediately after being used in high risk neonates 

• Premature neonates receiving treatment through feeding tubes and endotracheal tubes had increased levels of DEHP in their urine  

• Within six hours, neonates receiving lipid-based infusates through a PVC line received a DEHP dose exceeding the lower limit of the tolerable total daily intake. 

What did the new study show? 

The study by Welsch et al, was the largest to date on the impact of phthalates and preterm birth. The team analysed data from over 6 000 pregnant women in the United States to better understand the link between phthalate exposure and pregnancy.  

It found that women with higher concentrations of phthalates in their urine were more likely to deliver preterm babies. 

For the study, the researchers pooled statistics from 16 studies conducted across the United States that included data on individual phthalate levels as well as the timing of the mothers' deliveries, with the data spanning from 1983 to 2018. About 9% of the women delivered premature babies, with phthalate by-products detected in over 96% of those urine samples. 

The study, published in JAMA Pediatrics, examined 11 different phthalates found in the pregnant women, and discovered that four of them were associated with a 14% to 16% greater probability of having a premature baby.  

The team concluded that reducing the level of phthalates exposure by 50% could prevent preterm births by 12%, on average. The interventions focused on specific changes, such as choosing phthalate-free products, companies reducing the number of phthalates in their products voluntarily or changing regulations that would reduce exposure to these chemicals. A number of phthalate-free medical devices and equipment is available. 

REFERENCES: 

Anil KC. Low birth weight and its associated risk factors: Health facility-based case-control study. PLOS One, 2020. 

Anto EO, et al. Prevalence and Risk Factors of Preterm Birth Among Pregnant Women Admitted at the Labor Ward of the Komfo Anokye Teaching Hospital, Ghana. Front Glob Women’s Health, 2022. 

Jeena PM, et al. Maternal demographic and antenatal factors, low birth weight and preterm birth: findings from the mother and child in the environment (MACE) birth cohort, Durban, South Africa. BMC Pregnancy and Childbirth, 2020.  

Ruzickova K, et al. Preventing Harm from Phthalates, Avoiding PVC in Hospitals. Health Care Without Harm, 2014. https://noharm.org/sites/default/files/lib/downloads/pvc/Preventing_Harm_From_Phthalates.pdf 

Welch BM, et al. Associations Between Prenatal Urinary Biomarkers of Phthalate Exposure and Preterm Birth. A Pooled Study of 16 US Cohorts. JAMA Pediatr, 2022.