Corrected entry: The typewriter Jake is typing on near the end of the movie is a small IBM Selectric, a different model than the one seen earlier in the film.
Corrected entry: At the barbeque, when the parents pester the couple about having children, Christie's father tells them how she was born breech. Later in the movie, Christie has her baby and and it is also breech. The problem is that the doctors don't know until the last second. Wouldn't they have had a sonogram months before? Also, the fact that she was born breech indicates that the doctors would have been watching out for that. Babies don't breech themselves at the last second. [I think babies do turn just prior to birth.]
Correction: Most pregnancies have a routine ultrasound at 18-20 weeks, although that wasn't as "routine" when this movie was made, and babies turn many times after that point. There's no reason to be monitoring her, breech babies are not genetic. And yes, a baby can turn breech in the last few days of pregnancy or even during labor.
Correction: He's had plenty of time to purchase a new typewriter to complete his manuscript.
CocoCami