A pregnant woman’s exposure to BPA may potentially increase the risk of delivering babies with low birth weights, according to a new study from China.

During the course of the study, which ran from 2012 to 2014, 452 mother-infant pairs were selected from Wuhan, the most populous city in Central China. Urine samples were collected from the mothers at delivery and measured for bisphenol-A (BPA). Using birth weight data obtained from medical records, the researchers then evaluated the relationship between urinary BPA levels and low birth weight.

They found that mothers of newborns with lower birth weights had significantly higher BPA levels in their urine than the control mothers, according to the study published this month in Environment International.

They also found that the association between low birth weight and higher BPA levels was more pronounced among the female babies, suggesting female babies might be more susceptible to BPA than males.

The study, the first of its kind in China, adds to growing evidence that fetal exposure to BPA might cause developmental problems.

BPA is an endocrine-disrupting chemical that can act like estrogen in the body. Human and animal studies have linked the chemical to reproductive, behavioral and endocrine effects.

Even the most diligent mothers-to-be may find it challenging to avoid contact with BPA. It is ubiquitous—used to make polycarbonate plastics and commonly found in food and drink packaging, and in thermal receipts.

The study doesn’t prove BPA caused the low birth weights. Low birth weight can happen for a number of different reasons.

However, it is concerning as babies with low birth weights may be more at risk for other health problems, such as increased susceptibility to disease and infection, or longer-term problems such as learning disabilities or delayed motor and social development.