# Maternal-Foetal Effects of Exposure to Bisphenol A: Outcomes and Long-Term Consequences
## 5 Maternal-Foetal Effects of BPA
### Foetal Reproductive Function
The participants recruited underwent amniocentesis due to medical reasons (15-22 weeks), the infants' birth weights were recorded, and the biological samples were divided according to foetal birth weight into appropriate, small and large for gestational age. The authors found that maternal BPA exposure was positively related to birth weight centles and negatively associated with gestational age in full-term pregnancies, concluding that BPA may influence foetal growth velocity [82]. A similar investigation was conducted by [PERSON] and coworkers, where BPA was quantified in second-trimester amniotic fluid and correlated with birth weight in infants from full-term pregnancies [83]. However, this study gathered a larger population with 130 pregnant women, and the results showed that low levelsof BPA in amniotic fluid (0.40-2.0 ng/mL) were significantly correlated with a decrease in birth weight, opposite to the previous study by [PERSON] et al. where similar levels of BPA (0.109-1.605 ng/mL) were positively related with birth weight [82; 83]. As there are only two studies and with contradictory results, there is a need to invest in this subject, quantifying the levels of BPA in the amniotic fluid, which, despite being difficult to collect, allows for analysing maternal-foetal exposure at such a vulnerable time. Considering that most studies analyse the effects of specific individual classes of bisphenols and that possibly the adverse effects are potentiated due to multiple EDC exposure, [PERSON] et al. investigated the association between mixtures of bisphenols with birth outcomes [84]. From 2017 to 2019, one-spot urine samples from 180 pregnant women were collected for bisphenols quantification and analysed for birth weight and gestational age. As in the study by [PERSON] et al. [80], [PERSON] and colleagues also showed that BPA had the highest levels in urine compared to BPF and BPS. Nevertheless, a positive significant association between BPF levels and birth weight was found, while the bisphenol mixture was negatively related to birth weight. These results suggest that maternal bisphenol exposure may influence birth weight, though with different effects in individual or mixture exposure [84]. As previously described, [PERSON] et al. analysed the correlation between unconjugated BPA and BPA glucuronide levels in maternal and umbilical cord plasma with birth outcomes, where higher exposure to unconjugated BPA in the first trimester was associated with a reduction in birth weight. A sex-specific relationship was also found, considering that there was a greater birth weight reduction in female compared to male infants [66]. DNA methylation is an epigenetic mechanism that has been shown to be altered by BPA exposure in different studies [85; 86; 87]. However, in the context of maternal BPA exposure and its impact on birth parameters, the data were scarce. Thus, to overcome this gap, [PERSON] and colleagues analysed prenatal BPA exposure on maternal/foetal DNA methylation levels and the relationship with birth weight [88]. For this, urine samples were collected from 162 pregnant women for BPA quantification, and then, those with the lowest (8 participants) and highest (26 participants) BPA levels throughout the three trimesters were selected for DNA methylation measurement in blood samples. Additionally, 82 cord blood samples were also collected and pyrosequenced for the selected cytosine-guanine dinucleotide (CpG) sites, where methylation occurs predominantly. The analysis of prenatal BPA exposure, DNA methylation, and birth weight found an association between BPA levels in the second trimester and DHRS9 (dehydrogenase/reductase (SDR family) member 9) gene methylation in cord blood with low birth weight. These results suggest an increased risk of low birth weight after prenatal BPA exposure, possibly due to DNA methylation; however, further studies are needed to corroborate these results and to unravel the potential epigenetic mechanisms of BPA [88].