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Histopathology of placenta with increased syncytial knotting of chorionic villi, with two knots pointed out. The following characteristics of placentas have been said to be associated with placental insufficiency, however all of them occur in normal healthy placentas and full term healthy births, so none of them can be used to accurately diagnose placental insufficiency: [citation needed]
Ectopic pregnancy is a complication of pregnancy in which the embryo attaches outside the uterus. [5] Signs and symptoms classically include abdominal pain and vaginal bleeding, but fewer than 50 percent of affected women have both of these symptoms. [1]
It begins between the 4 and 8 weeks of pregnancy and usually subsides by 14 to 16 weeks. The exact cause of nausea is not fully understood but it correlates with the rise in the levels of human chorionic gonadotropin , progesterone , and the resulting relaxation of smooth muscle of the stomach.
Intrauterine hypoxia can be attributed to maternal, placental, or fetal conditions. [12] Kingdom and Kaufmann classifies three categories for the origin of fetal hypoxia: 1) pre-placental (both mother and fetus are hypoxic), 2) utero-placental (mother is normal but placenta and fetus is hypoxic), 3) post-placental (only fetus is hypoxic).
Infant weight loss greater than 10% of initial birth weight during the first 72 hours of life is observed in infants with mothers experiencing DOL. [9] Although neonatal weight loss is a normal physiological process where the infant excretes extra extracellular fluids accumulated pre-birth, it typically should not exceed 10% of birth weight. [ 7 ]
Besides placenta previa and placental abruption, uterine rupture can occur, which is a very serious condition leading to internal or external bleeding. Bleeding from the fetus is rare, but may occur with two conditions called vasa previa and velamentous umbilical cord insertion where the fetal blood vessels lie near the placental insertion site unprotected by Wharton's jelly of the cord. [11]
Human embryology is the study of this development during the first eight weeks after fertilization. The normal period of gestation (pregnancy) is about nine months or 40 weeks. The germinal stage refers to the time from fertilization through the development of the early embryo until implantation is completed in the uterus.
The sex of the fetus may be discerned by ultrasound as early as 11 weeks' gestation. The accuracy is relatively imprecise when attempted early. [15] [16] [17] After 13 weeks' gestation, a high accuracy of between 99% and 100% is possible if the fetus does not display intersex external characteristics. [18]