Are you starting to look pregnant? Week 14 is when most women "pop," or begin to show. This occurs because your uterus is atop your pubic bone, which may be pushing your belly out a bit. Unfortunately, week 14 may also bring another unwanted symptom: constipation. Pregnancy slows your digestive system, and your regular dosage of prenatal vitamins contains iron. Though iron is vital to preventing anemia, it can also contribute to constipation.