A pregnant woman's financial worries about the arrival and care of her little one could contribute to the birth of a smaller infant, a new study suggests.

"There is an opportunity here to look for interventions during pregnancy that could help mitigate the effect of financial strain on birth outcomes," said lead author Amanda Mitchell from the Ohio State University in the US. While larger efforts to improve access to housing, jobs and support for low-income women is critical, there are potential low-cost and stress-reduction techniques that could help reduce risk, Mitchell said. 

Meditation and breathing exercises could prove useful, she said. The study, published in the journal Archives of Women's Mental Health, included 138 pregnant women who filled out questionnaires to assess financial strain, depressive symptoms, pregnancy-specific distress, perceived stress and general anxiety. 

The participants were between 5 and 31 weeks pregnant and 29 years old on average at the time of the assessment. The study ran from 2013 to 2015. After the participants' babies were born, researchers were able to review medical records to compare birth weight against the questionnaire responses during pregnancy.

The study showed that pregnancy-specific distress, such as concerns that the baby's needs won't be met, could partly explain why pregnant women who are socioeconomically disadvantaged have a higher likelihood of having smaller babies and worse birth outcomes. Low-birth-weight babies often suffer from serious health problems and spend their first weeks or months in intensive care.