The plane would have had an emergency landing:) especially with an at risk child…
There is no way this would have been allowed. Baby’s born with Down’s syndrome are high risk- often have medical problems as well,40% have serious heart problems.
Her is a link to rules and advice for een not at high risk pregnancies.
http://www.pregnancy-info.net/wellbeing_flying.html  ” the American College of Obstetricians and Gynecologists (ACOG) recommends women don’t fly after their 36th week of pregnancy….LABOR… While the crew is likely trained for just such an emergency, or at least to help with childbirth, your flight will probably make an emergency landing at the closest airport to make sure you get the medical attention you need. “