ArnoldChiari malformation is a structural defect which leads to underdeveloped brain and a distorted spine.
A bench headed by Justice A K Sikri relied on a report of the medical board of Mumbai-based J J Hospital, where the two women were examined, and noted that the abnormalities in both the foetuses were identical and continuation of pregnancy would harm them.
While the first woman's foetus was 29-week old, the second woman was in 30th week of her pregnancy.
The women, both Mumbai residents, had approached the apex court seeking its permission to abort her foetus on the ground that it was suffering from severe anomaly.
Section 3(2)(b) of the Medical Termination of Pregnancy (MTP) Act prohibits abortion of a foetus after 20 weeks of pregnancy.