Immune system
The placenta functions as a maternal-fetal barrier against the transmission of microbes. When this is insufficient, mother-to-child transmission of infectious diseases can occur. Maternal IgG antibodies cross the placenta, giving the fetus passive immunity against those diseases for which the mother has antibodies. This transfer of antibodies in humans begins as early as the fifth month (gestational age) and certainly by the sixth month. Developmental problems
A developing fetus is highly susceptible to anomalies in its growth and metabolism, increasing the risk of birth defects. One area of concern is the lifestyle choices made during pregnancy. Diet is especially important in the early stages of development. Studies show that supplementation of the persons diet with folic acid reduces the risk of spina bifida and other neural tube defects. Another dietary concern is whether breakfast is eaten. Skipping breakfast could lead to extended periods of lower than normal nutrients in the maternal blood, leading to a higher risk of prematurity, or birth defects. Alcohol consumption may increase the risk of the development of fetal alcohol syndrome, a condition leading to intellectual disability in some infants. Smoking during pregnancy may also lead to miscarriages and low birth weight (2,500 grams (5 pounds 8 ounces). Low birth weight is a concern for medical providers due to the tendency of these infants, described as "premature by weight", to have a higher risk of secondary medical problems.
It takes advantage of the differential resistance of foetal hemoglobin to acid. A standard blood smear is prepared from the mothers blood, and exposed to an acid bath. This removes adult hemoglobin, but not foetal hemoglobin, from the red blood cells. Subsequent staining, using Shepards method, makes fetal cells (containing foetal hemoglobin) appear rose-pink in color, while adult red blood cells are only seen as "ghosts". 2000 cells  are counted under the microscope and a percentage of foetal to maternal cells is calculated. Fetal-maternal haemorrhage can also be diagnosed by flow cytometry, using anti-foetal hemoglobin antibodies (anti-HbF). Treatment
If ongoing and rapid haemorrhage is occurring then immediate delivery of the foetus may be indicated if the fetus is sufficiently developed. If the  haemorrhage has already occurred and now stopped, an inutero transfusion of red cells to the foetus may be recommended. References


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