I hate to interject with reality, but labor usually only takes a few hours. Pregnant women generally go about their days just fine thank you
Normal families with two or three children have problems if two kids are born a year and a half apart;
You seem unaware that for the vast bulk of human history families this have size been pretty normal across all cultures. Really you should read more.
the mother has a new baby to deal with right at the point at which the first kid should be taking the biggest steps in learning how to talk. Even bright kids can check out as mildly retarded at age 5 - 6 on account of that.
Here's a clue - the father is also there much of the time and the other children are well spoken and do just fine for teaching language skills.
On a different note - Age difference between 1 and 2 - 14 months. Child 1 was speaking like an adult by age 2. Child 2 was also speaking complete sentences by age 2. Child 3 (2.4 years between 2 and 3) took longer, because his siblings did his talking for him.
All are honors students, top of their classes.