The mother's stress physiology before she even conceives is also important, even before a woman becomes pregnant, her stress physiology may predict a lower-birth weight of baby -- less than 2.5 kg, said a new study.
It suggests that a woman's health and life circumstances before her pregnancy, especially chronic stress, matter greatly. "We found that the same cortisol pattern that has been linked with chronic stress is associated with delivering a baby that weighs less at birth," said lead author Christine Guardino from the University of California in the US.
Researchers claim this study first evidence that shows maternal cortisol -- a hormone the body releases in response to stressful events -- patterns before conception influence the weight of the baby.
"Women's cortisol levels typically increase by two to four times during a normal pregnancy and that increase plays an important role in a baby's growth and development, said co-author Chris Dunkel Schetter.
But when cortisol levels are elevated beyond that range, the effects can be both immediate -- because elevated cortisol levels reduce blood flow to the foetus -- and longer-lasting -- influencing the child's response to stress later in life, Schetter explained."
The results showed that the women were likelier to give birth to lower-weight babies. They have a higher-than-normal risk for infant mortality developmental and for health abnormalities throughout their lives, including cardiovascular and metabolic disorders.
Women planning a pregnancy should take into account the possible effects of everyday stress and begin planning for a healthy first pregnancy well in advance, Schetter added.