Question

After examining the blood groups of husband and wife, the doctor advised them not to have more than one child. The blood groups of the couple are likely to be
(a) Male $R{ h }^{ - }$ and female $R{ h }^{ + }$
(b) Male $R{ h }^{ + }$ and female $R{ h }^{ + }$
(c) Female $R{ h }^{ - }$ and male $R{ h }^{ + }$
(d) Male$R{ h }^{ - }$ and Female $R{ h }^{ - }$

Answer 1

Hint: It is possible that the blood groups of the pair are as follows. When the antiserum agglutination takes place in the father's red blood cells and the mother's red blood cells are not agglutinated.

Complete step by step answer:
$R{ h }^{ + }$ husband and $R{ h }^{ - }$ wife could have $R{ h }^{ + }$ 1st baby. In an Rh-mother, the mixing of $R{ h }^{ + }$ blood (from the child) allows the mother to build up certain antibodies against the $R{ h }^{ + }$ blood cells in her blood over time. These antibodies will then cross over through the placenta (afterbirth) to the baby and kill the baby's blood cells. $R{ h }^{ + }$ babies are likely to be infected by the mother's antibodies in subsequent pregnancies. In these cases, it is, therefore, advisable to have no more than one child.
So, the correct answer is, ‘Female $R{ h }^{ - }$ and male $R{ h }^{ + }$’.

Additional information:
This difference in the Rh factor of the mother will attack the fetus’s blood cells and cause its death. This disease is referred to as Erythroblastosis foetalis.
Since a $R{ h }^{ + }$ father may have either DD or Dd genotype, there are 2 mating combinations possible with different risks. Regardless of the genotype of the parent, if he is $R{ h }^{ + }$ and the mother is $R{ h }^{ - }$, doctors presume that an incompatibility issue will arise and behave accordingly.
Bear in mind that there are possibly just medical risks for $R{ h }^{ + }$ kids (Dd). The birth would be natural if both the mother and her fetus are $R{ h }^{ - }$ (dd).
The Rh method was named after rhesus monkey, as they have been originally used to make the antiserum for blood sample typing in the study. You are $R{ h }^{ + }$ if the antiserum agglutination the red cells. If it doesn't, then you're $R{ h }^{ - }$.

Note: Karl Landsteiner and Alexander Wiener discovered the ${Rh}$ blood types in the year 1940. This was 40 years after the ABO blood types were discovered by Landsteiner. This blood group may be the most genetically complex of all blood type systems, since 45 different red cell surface antigens are involved, regulated by 2 closely related genes on chromosome 1.