Police said on Friday that the women were disappointed that both the babies were girls. They feared the family would incur a huge expenditure in their medical treatment, since they were born premature.
According to police, Revathy (21), wife of an autodriver in Thoothukudi district, was eight months pregnant. She went into labour on September 23 and was rushed to the district government hospital where she delivered the twins. The babies weighed about two kg each.
The doctors kept the newborns in an incubator and the babies were brought out only for breast-feeding. According to the police, on Thursday morning, Revathy and her mother Thennila (45), had taken the infants for feeding after informing the nurse. After being with the infants for a while, they rushed back to the incubator room and created a commotion, demanding to know what the nursing staff had done to the babies, as they were unconscious.
The hospital's chief maternity officer Lourdes Alpino, who checked the babies, found traces of blood on one of them and became suspicious and informed the police.
The mother and grandmother later reportedly confessed to having killed the infants.