(i) By amniocentaesis.
(ii) Amniotic fluid is taken out aseptically from the amniotic sac and the cells contained in it are subjected to chromosomal analysis.
(iii) Disclosing the sex of the foetus is banned in our country because of its misuse resulting in the increasing cases of female foeticide:
(iv) The doctor is ethical, dutiful and is devoted to his duties.

(b) Mode of action of IUDs
(i) Increase phagocytosis of sperms within the uterus.
(ii) Cu⁺⁺ released suppress sperms motility/fertility capacity of sperm.
(iii) Hormone releasing IUDs make uterus unsuitable for implantation/cervix hostile to the sperms.

(i) One can know the sex of the foetus by amniocentesis.
(ii) During the process of amniocentesis, a sterile needle is inserted through the abdominal wall into the amniotic sac. Then, a small amount of amniotic fluid is withdrawn through the needle.
The fluid contains cells, which are separated from the amniotic fluid. Tests are then performed on cultured cells by chemical analysis, DNA analysis, and chromosomal analysis.
(iii) Disclosing the sex of the foetus is banned in our country because, in the past, there have been numerous cases, where the female foetud has been aborted. this discrimination for the girl child is considered a crime. the number of females to males ration is thereby reduced.
(iv) the doctor is devoted to his duties and has professional and moral ethics.

Differences between natality rate and mortality rate

Population density.  Population density of a species is the number of individuals of a species per unit area or volume e.g., number of animals per square kilometer; number of trees per acre of a forest etc. For instance, number of people per square kilometer in 1991.If the total number of individuals is represented by letter N and the number of units of space by letter S, the population density D can be obtained as D = N/S.
Consequences of Higher Population density
As the population density increases in a country beyond its means; it brings following problems:
1. per capita income comes down
2. natural resources like land, minerals, wood, fuel, etc. decrease
3. general health goes down
4. The large population of a country is the result of having large families and the quality of life gets deteriorated accordingly.

Demography.   The scientific study of human population is called demography.It deals with three phenomena:
(i) Changes in population, i.e., growth or decline.
(ii) Composition of the population, i.e., age groups, sex ratios.
(iii) Distribution of population in space.
Demographic study is carried out through census,  registration of births and deaths.

Sex education in the school must be encouraged as it provides right information to the students about following aspects of reproductive health:
(i) Paris and functioning of various parts of reproductive system.
(ii) Removes certain myths and misconceptions about sex-related aspects.
(iii) Informs about safe and hygienic sexual practices.
(iv) Informs about adolescence and related problems.
(v) Informs about causes, mode of occurrence and preventive measures of STDs, AIDS,etc.

(i) Mode of Action.     Oestrogen inhibits ovulation by preventing FSH production.
(ii) Advantages.   Hormonal contraceptives are super devices to prevent conception.
(iii) Disadvantages.   They disturb the menstrual cycles.

Counseling and creating awareness among people about the following aspects would help in building up a reproductively healthy society
(i) Reproductive organs
(ii) Adolescence and associated changes
(iii) Safe and hygienic sexual practices and
(iv) Sexually transmitted diseases
Educating people, especially fertile couples and those in marriageable age group about the following would help to raise a socially responsible society.
(i) Available birth control methods
(ii) Care of pregnant mothers
(iii) Importance of breast feeding and
(iv) Equal opportunities for a girl child.