Why did she say that ?

I do not think that was the reason, because she said : we can't have sex..she did not say im not in the mood or i would not do it..she said we can't !

wow, 4-6 weeks ?? that is a long time, i wonder how husbands can wait that long without cheating, not to mention the last month of pregnancy is a disaster in terms of having sex..
by the way, im married, but i was wondering how americns deal with the post pregnancy period..thanks anyways

Something that really annoyed me in this film (and often does in films) is that she doesn't look like she had a baby recently - perfectly flat stomach. Not realistic! Makes me want to slap someone upside the head!!! Also, she would still be in the postnatal bleed - no way could she wear those skimpy panties with a maternity pad (sanitary pad), which she *would* be wearing *if* they bothered to make this aspect true to reality (tampons are not appropriate for the same reason that sex is not appropriate).

The other thing that really bugged me is when you first see Joshua looking at his parents with the baby - it seems like the parents haven't done anything to prepare him for the imminent arrival of a sibling. A scene or two involving Joshua and his parents while his mother is still pregnant would have been useful.

It is recommended that women abstain from intercourse for 6 weeks after giving birth. Most women ignore this recommendation, but yes, 31 days after giving birth, should still be in the "hands-off" window.

I don't know about "supposed to" however your doctor will usually give you a recommendation about when it is OK to begin having sex again after birth. Typically, this will be in the neighborhood of six weeks. I took the text below from a answers to pregnancy website:

The uterus and cervix undergo significant changes during the process of delivering a baby, and they need time to heal. During this healing phase the lining of the uterus, especially the site where the placenta was attached, is susceptible to infection. Intercourse, douching, tampons, and anything placed in the vagina may introduce bacteria, and cause an infection. The flow of lochia, which is a sign that the lining is healing, can last from three to eight weeks. When the lochia flow is no longer bright red, it signals that healing is near completion, and it's probably safe to have intercourse again.

Many other factors can affect the amount of time you should wait. A vaginal laceration, rectal tear or epesiotomy can take three weeks or longer to heal, depending on the severity of the injury. If you have intercourse too soon you can cause not only pain but a disruption in the healing process, and even cause another rupture in that area.

If you have had a C-section, you have undergone major abdominal surgery, and your body will need sufficient amounts of time to recover before resuming normal activities, including sex.

Anyway, hopefully that answers your question.