The structure of DNA lends itself easily to DNA replication. Each side of the double helix runs in opposite (anti-parallel) directions. The beauty of this structure is that it can unzip down the middle and each side can serve as a pattern or template for the other side (called semi-conservative replication).
Rupture of the uterus during pregnancy or labor is a serious emergency that can be fatal to both mother and fetus. Uterine rupture results in: 1  bleeding; 2  rupture of the amniotic sac (bag of waters); 3  partial or full delivery of the fetus into the abdominal cavity; and. 4  loss of oxygen delivery to the fetus.
Probably the most dangerous cause for bleeding during the 1st trimester is an ectopic pregnancy. Ectopic pregnancy occurs when your fertilized egg implants somewhere outside the uterus--usually the fallopian tube--and begins growing. (Ectopic means out of place.) Typically this happens if your fallopian tube is blocked by scar tissue or has an abnormality. Eventually the abnormal pregnancy will grow and could cause the tube to rupture; if this occurs, severe abdominal pain and bleeding will result.