FRIDAY, July 26, 2013 (HealthDay News) -- Infants who spent at least one night a week away from their mothers had weaker bonds with their mothers than infants who were with their mothers every night, a new study finds.
The findings are important in light of the growing number of American parents who don't live together and have some form of joint custody, said study lead author Samantha Tornello, a doctoral candidate in psychology at the University of Virginia.
She and her colleagues analyzed data from thousands of children born in large U.S. cities between 1998 and 2000. Among parents who were not living together, about 7 percent of babies who were less than 1 year old and lived primarily with their mothers spent at least one overnight a week away with their fathers.
Among toddlers aged 1 to 3, about 5 percent spent between 1 percent and 35 percent of overnights away with their fathers. And nearly 7 percent spent 35 percent to 70 percent of overnights with their fathers.
For babies whose primary caregivers were their mothers, those who spent at least one overnight a week away with their fathers had more insecure attachments to their mothers than those who had fewer overnight stays with their fathers or spent time with their fathers only during the day -- 43 percent vs. 16 percent.
The findings were not as strong among toddlers, according to the study in the August issue of the Journal of Marriage and Family.
Although the study tied overnight separation to less secure attachment in babies with their mothers, it did not establish a cause-and-effect relationship.
Attachments are defined as an enduring, deep, emotional connection between an infant and caregiver that develops within the child's first year of life, according to Tornello. Attachments during the first year of live form the basis for healthy attachments and relationships later in life, even in adulthood.
While the primary caregivers in this study were mothers, fathers can also be primary caregivers, Tornello noted.
"We would want a child to be attached to both parents, but in the case of separation a child should have at least one good secure attachment," she said in a university news release. "It's about having constant caregivers that's important."
The Nemours Foundation has more about bonding with your baby.