Rh incompatibility in a mother who has never been sensitized

Erythroblastosis fetalis happens when an Rh-negative mother carries an Rh-positive fetus; if fetal blood mixes with hers during delivery or a procedure, she can develop antibodies that attack fetal hemoglobin in a later pregnancy, causing hemolysis, anemia, and hyperbilirubinemia in that newborn. For a mother who is not yet sensitized, confirmed by a negative indirect Coombs test, Rho(D) immune globulin (RhoGAM) is given at 28 to 30 weeks; if the newborn's cord blood direct Coombs test then comes back positive, a second dose follows within 72 hours postpartum. This is the same drug given twice, tied to two specific negative and then positive test results, not given automatically.

CORRECTED

A mother whose first infant was already born with erythroblastosis fetalis is a different case entirely: that history means she is already alloimmunized, and her antibody screen is positive. RhoGAM works only by blocking the first immune recognition of Rh-positive cells, before antibodies exist; it cannot remove antibodies that are already there, and a positive antibody screen is the reason not to give it, not a reason to give it on the old 28-week/postpartum schedule. Care for an already-sensitized pregnancy is antibody titres, referral to maternal-fetal medicine, and serial fetal middle cerebral artery Doppler surveillance from about 16 to 18 weeks, with intrauterine transfusion if the Doppler shows significant fetal anemia. Risk to this fetus is usually higher than in the first affected pregnancy, not equal to it, and waiting for neonatal jaundice after birth means waiting past the point where these interventions still work.

Neonatal hypoglycemia

An infant of a diabetic mother keeps producing the extra insulin it made in utero after the maternal glucose supply stops at birth, causing hypoglycemia (glucose below 45 mg/dL), first jittery and irritable, then lethargic, with poor feeding. It is highly preventable brain damage: the response is to breastfeed immediately, or give glucose water or formula, with IV glucose if the newborn can't suck, not to wait four hours and recheck, and not to treat it as a warming problem.