Course 21.1Lesson 1 of 3

Reproductive health and the growth of a population

Reproductive health means well-being in every part of reproduction: body, feelings, behaviour and society. This lesson explains what a country does to protect it, why the numbers of people grew so fast, and how a growth rate is turned into a doubling time.

about 30 min1 simulation1 practice question

Lesson 1 of 3Show all lessons

Try the code and the simulations beside the lesson.

A poster at the health centre

Most of us have seen a poster at a health centre or in a school. It may speak about a safe pregnancy, about the vaccines of a baby, or about the changes of growing up. All of these belong to one idea: reproductive health.

The World Health Organization (WHO) describes it as a state of total well-being in all aspects of reproduction. These aspects are physical, emotional, behavioural and social. So reproductive health is more than the absence of a disease.

A society is reproductively healthy when its people have normal reproductive organs, and when their feelings and behaviour in all matters of sex and reproduction are healthy too.

What a country does about it

India was among the first countries to start a national plan for reproductive health. The programmes called family planning began in 1951. They were improved over the years. The wider programme that works today is called Reproductive and Child Health Care (RCH).

The main steps are these.

Awareness. People are given correct information about the reproductive organs, adolescence, safe and hygienic practices, birth control and sexually transmitted infections (STIs).
Sex education in schools. Young people are told the facts, so that they do not believe myths or wrong ideas.
Care of the mother and the child. Care in pregnancy, safe delivery, care after birth, and the importance of breast-feeding.
Medical facilities. Care for problems of pregnancy and delivery, for contraception, for menstrual problems and for infertility.
Equal chances. Equal opportunity for the male and the female child.
Law. A statutory ban on the use of amniocentesis to find the sex of an unborn child. You meet this in the next course.

These steps also try to make people aware of the problems of fast population growth, and of sex abuse and sex-related crimes.

The growth of the population

Two bar charts side by side. The left chart, World population in billions as NCERT gives it, has three bars: 2 billion in 1900, 6 billion in 2000 and 7.2 billion in 2011. The right chart, India population in billions as NCERT gives it, has three bars: 0.35 billion in 1947, 1 billion in 2000 and 1.2 billion in 2011.

NCERT gives these numbers. The world population was about 2 billion in 1900. It rose to about 6 billion in 2000 and to 7.2 billion in 2011. In India, the population was about 350 million at independence. It came close to 1 billion in 2000 and crossed 1.2 billion in 2011.

A note on newer numbers. The United Nations estimates that the world passed 8 billion people in 2022. These later values are not needed for the NCERT questions, but they show that the growth has not stopped.

What caused the rise? NCERT names three causes: a fall in the death rate, a fall in the maternal mortality rate (MMR), and a fall in the infant mortality rate (IMR). Better food and health care kept more people alive. At the same time, the number of people of an age to have children (the reproducible age group) grew.

A large and fast growing population puts a load on food, water, housing, schools and health care. This is why a country tries to keep the numbers steady. NCERT calls it population stabilisation. The measures include these.

Awareness through schools and mass media about small families.
A legal minimum age of marriage: 18 years for a female and 21 years for a male.
Incentives for couples with small families.
Wide, easy access to methods of birth control. The rest of this course describes them.

From a growth rate to a doubling time

A growth rate says by what share a population grows each year. If a rate is $r$ per cent a year, the population is multiplied by $1 + \dfrac{r}{100}$ every year. After $t$ years, the population is

\displaystyle P = P_0 \left(1 + \dfrac{r}{100}\right)^t

where $P_0$ is the starting population. The time to double comes from setting $P = 2P_0$ :

\displaystyle t_{\text{double}} = \dfrac{\ln 2}{\ln\left(1 + r/100\right)}

A quick rule, the rule of 70, says that $t_{\text{double}} \approx \dfrac{70}{r}$ years. At 2 per cent a year the exact time is 35.0 years, and the rule gives 35 years.

A note on printed values. Books may print a doubling time for a rate "near 2 per cent". Check the rate that goes with the time. A rate of 2.1 per cent gives about 33 years, and 2.0 per cent gives 35 years.

A graph of population against time in years, from 0 to 60 years, for a population that starts at 100. Three rising curves show growth of 1, 2 and 3 per cent a year. A dashed horizontal line marks double the start, at 200. Each curve meets the dashed line at its doubling time: about 70 years for 1 per cent, about 35 years for 2 per cent and about 23 years for 3 per cent. After 60 years the 3 per cent curve is the highest, at about 590.

You should find that a low rate gives a long doubling time and a high rate a short one. A rate of 3 per cent doubles a population in about 23 years.

Try it in Python

The program lets a population grow by the same share each year, and finds the doubling time in two ways.

Practise with new numbers

Common mistakes

Saying that reproductive health only means having no disease. It includes physical, emotional, behavioural and social well-being.
Adding the same number every year. A population grows by a share, so each year's growth is larger than the last. Use a power.
Putting the rate in the formula as 2 instead of 0.02. Divide a per cent by 100 first.
Mixing up the two programmes. Family planning began in 1951. The later and wider programme is RCH.
Writing the doubling time as 100 divided by the rate. That would give 50 years for 2 per cent. The rule is 70 divided by the rate.

Remember these

Reproductive health: total well-being in all aspects of reproduction, which are physical, emotional, behavioural and social (WHO).
India began family planning in 1951. The present programme is Reproductive and Child Health Care (RCH).
Fall in the death rate, MMR and IMR, and more people of reproducible age, caused the rapid rise of the population.
Statutory marriage age: 18 years for a female and 21 years for a male.
Doubling time $= \dfrac{\ln 2}{\ln(1 + r/100)}$ , close to $\dfrac{70}{r}$ years.

Check yourself

Try each one on your own first. If you are stuck, open a hint. Then check with Show the answer.

What does the WHO mean by reproductive health?

In which year did India begin its family planning programmes, and what is the wider programme of today called?

Why did the population of India rise so fast after independence?

Why is sex education in schools part of the plan?

A population grows by 2 per cent every year. About how long does it take to double?

References

NCERT (2023). Biology, Textbook for Class XII, chapter 3, Reproductive Health.
United Nations (1994). Programme of Action of the International Conference on Population and Development, Cairo, paragraph 7.2 (the description of reproductive health).
United Nations, Department of Economic and Social Affairs, Population Division (2022). World Population Prospects 2022.
Office of the Registrar General and Census Commissioner, India (2011). Census of India 2011.