(CNN) -- Mothers who give birth using donor eggs may react less sensitively to their babies and have a lower confidence in their parenting ability, a study says.
Scientists at the University of Cambridge found "subtle yet meaningful differences" in the ways egg donor mothers interacted with their children, compared to mothers who had children using their own eggs.
The team interviewed 85 families who'd conceived using egg donation and 65 families who had children through the mother's own eggs.
They also observed mothers playing with their children as they normally would.
During interviews, mothers who used a donor's eggs were more likely to express a lack of confidence in their own parenting ability, the paper says. Changes were not detected in fathers.
The study suggests this may be associated with the older age of mothers who had used donor eggs.
Other differences included how quickly mothers read signals given by babies, such as boredom, and the study also noticed that egg donor infants were "less emotionally responsive and involving of the mother" than babies who were genetically related to their mothers.
"Egg donation mothers were responding slightly less sensitively and they were structuring their play slightly less" than mothers who had used their own eggs as part of in-vitro fertilization, the study's lead author, Susan Imrie, a research associate at the University of Cambridge, told CNN.
But the authors stressed that the overall cohesion and strength of relationships between mother and baby were not tested.
"The main takeaway is that the parents and babies are doing well," said Imrie. "Although we did find these subtle difference in the play task, egg donor mums and IVF mums did look more similar than different."
The authors did not suggest that mothers who used egg donors were less capable mothers, and the study is "no basis for saying anything much about child welfare," said Ellie Lee, director of the Centre for Parenting Culture Studies at the University of Kent. Lee was not involved in the study.
"These mums have no need to worry any more than they do already any more than they do already about themselves or their children," Lee added. "Overall, it's wonderful that technology allows women and men who otherwise would not be able to, to have children, and society would do well to keep its eye on this, rather than anything else."
An estimated 3,924 women underwent IVF using a donor egg in the UK in 2016, the last year for which figures are available, compared to 1,912 in 2006, according to the Human Fertilisation and Embryology Authority.
In the US, 76,930 total IVF births - including donor and non-donor eggs - occurred in 2016, according to the US Centers for Disease Control and Prevention.
Since the procedure became available 40 years ago, at least 8 million babieshave born using IVF worldwide. Today, more than two million treatment cycles from IVF and intracytoplasmic sperm injection are performed each year, resulting in half a million babies globally.
The-CNN-Wire
™ & © 2018 Cable News Network, Inc., a Time Warner Company. All rights reserved.
