Pregnancy and Childbirth

Erythroblastosis fetalis also called the hemolytic disease of the newborn, type of anemia in which the red blood cells (erythrocytes) of a fetus are destroyed in a maternal immune reaction resulting from a blood group incompatibility between the fetus and its mother. Symptoms of erythroblastosis fetalis range from mild to severe; death of the fetus or newborn sometimes results.

The Rh system is responsible for the most severe form of the disease, which can occur when a Rh-negative woman (a woman whose blood cells lack the Rh factor) conceives a Rh-positive fetus. Sensitization of the mother’s immune system (immunization) occurs when fetal red blood cells that carry the Rh factor (an antigen in this context) cross the placental barrier and enter the mother’s bloodstream. They stimulate the production of antibodies, some of which pass across the placenta into fetal circulation and lyse, or break apart, the red blood cells of the fetus (hemolysis). Hence option B is correct.

Thrombin is a serine protease that plays a central role in the blood coagulation cascade by converting soluble fibrinogen into insoluble fibrin strands.

There are two main causes of erythroblastosis fetalis: Rh incompatibility and ABO incompatibility. Rh incompatibility occurs when a Rh-negative mother is impregnated by a Rh-positive father. The result can be a Rh-positive baby. In such a case, your baby’s Rh antigens will be perceived as foreign invaders, the way viruses or bacteria are perceived. Your blood cells attack the baby’s as a protective mechanism that can end up harming the child. If you’re pregnant with your first baby, Rh incompatibility isn’t as much of a concern. However, when the Rh-positive child is born, your body will create antibodies against the Rh factor. These antibodies will attack the blood cells if you ever become pregnant with another Rh-positive baby.

Parturition is the act of expelling the full-term young one from the mother's uterus at the end of gestation. Gestation (pregnancy) is completed in about 266 days from the mother's last menstruation.

Parturition, also called birth or childbirth, process of bringing forth a child from the uterus, or womb. The prior development of the child in the uterus is described in the article human embryology. The process and series of changes that take place in a woman’s organs and tissues as a result of the developing fetus are discussed in the article pregnancy. Parturition is induced by a complex neuroendocrine mechanism. The signals for parturition originate from the fully-developed foetus and the placenta which requires the release of oxytocin from the posterior lobe of the maternal pituitary.

The delivery of the developed foetus after 9 months is known as parturition. Ovulation is the release of the secondary oocyte from the ovary. 

Parturition is the process of giving birth to the child.

It has been observed that by the end of the second month of pregnancy period, the foetus develops limbs and digits. Also, by the end of the first trimester (12 weeks), most of the major organs are developed, for instance, the limbs and external genital organs. The signals for parturition derives from the fully developed foetus and the placenta that further leads to mild uterine contraction referred to as foetal ejection reflex. By the end of pregnancy, the mammary glands initiate producing milk by the lactation process. 

• When a woman is in a lithotomy or semi-sitting position, the Foetal Ejection Reflux is impaired and the increased pain caused by the sacrum’s inability to move as the baby descends can be intolerable
  
• Foetal ejection reflex in human female is induced by fully developed foetus and placenta. so, option D is correct