Class 12 Biology · NCERT chapter 4 · 5 topics · free to read
Reproductive Health & Population
WHO defines reproductive health as total well-being in all aspects of reproduction — physical, emotional, behavioural, and social. India was the first country to launch a national family planning programme (1951). Population explosion is driven by declining death rates, improved healthcare, and increased life expectancy. RCH (Reproductive and Child Health Care) programmes aim for better awareness and facilities.
Population Growth Rate = Birth Rate - Death Rate + Net Migration
WHO Definition
Reproductive health means complete physical, emotional, behavioural, and social well-being in all matters relating to the reproductive system. India launched RCH programmes to achieve this goal.
According to WHO, reproductive health means a total well-being in all aspects of reproduction — physical, emotional, behavioural, and social. It's NOT just the absence of reproductive diseases or infirmities. A society is considered reproductively healthy when people have physically and functionally normal reproductive organs AND emotionally balanced behavioural interactions in all sex-related aspects.
WHO definition covers 4 dimensions: physical, emotional, behavioural, and social well-being
India's family planning programme started in 1951 — first in the world
Programme renamed to RCH (Reproductive and Child Health Care) to broaden the scope
Government agencies, NGOs, and WHO together work towards achieving reproductive health goals
Creating Awareness
Achieving reproductive health requires massive awareness campaigns through audio-visual media, print media, educational institutions, and government/NGO programmes targeting all age groups, especially adolescents.
Awareness about reproduction and reproductive health is spread through multiple channels: (1) introduction of sex education in schools to give correct information to adolescents, (2) government and NGO-led awareness campaigns through audio-visual media, print media, and seminars, (3) training of health workers to provide correct information and services at grassroot level.
Sex education in schools helps dispel myths and misconceptions about sex-related aspects
Awareness covers: adolescent reproductive health, available contraceptives, care of pregnant mothers, post-natal care
Educating fertile couples about birth control options, STDs, and importance of breastfeeding
Proper information helps people think and take informed decisions — not shy away from reproductive health topics
Fertile couples and marriageable age groups are special target groups
Population Explosion
India's population explosion is primarily due to rapid decline in death rate (DDR), maternal mortality rate (MMR), and infant mortality rate (IMR) due to better healthcare, while birth rate did not decline proportionally.
India's population was around 350 million at independence (1947) and crossed 1 billion by 2000. The primary cause? Death rate declined sharply due to improved healthcare, better nutrition, and disease control — but birth rate did not decline proportionally. This mismatch between birth rate and death rate = population explosion.
Rapid decline in death rate (DDR), maternal mortality rate (MMR), and infant mortality rate (IMR) are key causes
Better healthcare, vaccines, antibiotics, and sanitation → more people survive → population grows
Increased life expectancy from ~30 years (1947) to ~70 years today
Birth rate did NOT decline as fast as death rate → exponential population growth
According to 2011 census, India's population was about 1.21 billion with a growth rate of about 1.64%
Decline in death rate (better healthcare)
Scarcity of food and resources
Decline in infant mortality
Unemployment and poverty
Increased life expectancy
Environmental degradation
Birth rate did not decline proportionally
Insufficient housing and education
Early marriages and lack of education
Pollution and deforestation
Population Control Measures
Government uses multiple strategies: raising marriageable age (18F/21M), incentives for small families, promoting contraception, and strict enforcement against sex-selective abortions.
The Indian government has adopted a multi-pronged approach to control population: legal measures (statutory raising of marriageable age), motivational measures (incentives for small families), contraceptive distribution, and social measures (education of women, economic empowerment).
Statutory marriageable age: 18 years for females, 21 years for males
Incentives for couples with small families (tax benefits, priority in government schemes)
Promoting use of contraceptive methods with government-supplied free contraceptives
Educating women — strongly correlated with lower birth rates globally
Strict laws against sex-selective abortions (Pre-Conception and Pre-Natal Diagnostic Techniques Act, PCPNDT Act, 1994)
Current sex ratio (2011 census): 943 females per 1000 males — skewed due to female foeticide
Sex ratio is defined as number of females per 1000 males. A ratio below 1000 indicates more males — which is the situation in India due to sex-selective practices. Kerala has the best sex ratio (~1084).
Contraceptive Methods
Contraception prevents unwanted pregnancies through various methods: natural (rhythm method, coitus interruptus, lactational amenorrhea), barrier (condoms, diaphragm, cervical cap), IUDs (CuT, Cu7, LNG-20, Multiload 375), hormonal (oral pills, injectables, implants), and surgical (vasectomy in males, tubectomy in females). An ideal contraceptive should be user-friendly, reversible, with minimal side effects.
Ideal Contraceptive = Effective + Reversible + No Side Effects + Easy to Use
Natural Methods
Natural methods avoid conception without any artificial devices or drugs. They include periodic abstinence (rhythm method), coitus interruptus (withdrawal), and lactational amenorrhea.
Natural methods work on the principle of avoiding sexual intercourse during the fertile period or preventing sperm from reaching the egg without using any device or chemical. These are the oldest methods of birth control — free, with no side effects, but with high failure rates (up to 25%).
Periodic abstinence / Rhythm method: Avoid coitus from day 10 to 17 of the menstrual cycle (ovulation occurs around day 14, sperm survive ~3 days, egg survives ~1 day)
Coitus interruptus / Withdrawal: Male withdraws penis before ejaculation — high failure rate due to pre-ejaculatory fluid
Lactational amenorrhea (LAM): Absence of menstruation during intense breastfeeding (up to 6 months postpartum). High prolactin suppresses ovulation
LAM is effective only up to 6 months after delivery and only during full breastfeeding (no supplementary feeding)
Natural methods have no side effects but are the least reliable — failure rate 10–25%
Barrier Methods
Barrier methods physically prevent sperm from reaching the ovum. They include condoms (male and female), diaphragms, cervical caps, and vaults. Often used with spermicides for higher efficacy.
Barrier methods work by creating a physical barrier between sperm and egg. They are widely available, easy to use, and provide the added benefit of STD protection (especially condoms). They are made of rubber, latex, or polyurethane.
Male condoms: Thin rubber/latex sheath over the penis. Most popular contraceptive worldwide. Also protects against STDs
Female condoms (Femidom): Inserted into the vagina before coitus. Made of polyurethane
Diaphragm: Rubber dome inserted into the vagina to cover the cervix. Reusable
Cervical cap: Smaller than diaphragm, fits tightly over the cervix
Vaults: Similar to diaphragm but covers the vault of the vagina
Diaphragms, cervical caps, and vaults are used with spermicidal creams, jellies, or foams for higher effectiveness
Covers the penis
Covers the cervix
Disposable (single use)
Reusable
Protects against STDs
Does NOT protect against STDs
Made of rubber/latex
Made of rubber
Used with or without spermicide
Must be used WITH spermicide
No prescription needed
Needs proper fitting by doctor
IUDs
Intra-Uterine Devices (IUDs) are inserted into the uterus by a doctor. Three types: non-medicated (Lippes loop), copper-releasing (CuT, Cu7, Multiload 375), and hormone-releasing (LNG-20/Progestasert).
IUDs are devices inserted into the uterus through the vagina by a trained doctor or nurse. They are one of the most effective long-term reversible contraceptives — effective for 3–10 years depending on type. They work by making the uterine environment hostile to sperm and/or preventing implantation.
Non-medicated IUDs: Lippes loop — works by causing mild inflammatory reaction in uterus, preventing implantation
Copper-releasing IUDs: CuT (Copper-T), Cu7, Multiload 375 — Cu²⁺ ions are toxic to sperm, reduce sperm motility, suppress sperm capacitation
Hormone-releasing IUDs: LNG-20 (Levonorgestrel), Progestasert — release progesterone/levonorgestrel, thicken cervical mucus, make endometrium unreceptive to implantation
Cu²⁺ ions increase phagocytosis of sperm in the uterus
Hormone-releasing IUDs make the uterus unsuitable for implantation + thicken cervical mucus to block sperm
Release Cu²⁺ ions
Release progesterone/levonorgestrel
Cu²⁺ toxic to sperm
Thickens cervical mucus
Suppress sperm capacitation
Makes endometrium unreceptive
Increase phagocytosis of sperm
Also suppresses sperm motility
Non-hormonal — fewer systemic effects
Hormonal — may reduce menstrual flow
Hormonal Methods
Hormonal contraceptives use synthetic progestogen alone or a combination of progestogen + estrogen to prevent ovulation, alter cervical mucus, and make the endometrium unreceptive. Includes oral pills, injectables (Depo-Provera), implants (Norplant), and emergency pills (Saheli/Centchroman).
Hormonal methods use synthetic progesterone (progestogen) or a combination of progestogen + estrogen to suppress ovulation. They work by mimicking pregnancy hormones — the body 'thinks' it's already pregnant, so no new egg is released. They also thicken cervical mucus and make the endometrium unreceptive.
Oral pills (OCs): Contain progestogen alone or progestogen + estrogen. Taken daily for 21 days, followed by 7-day gap. Most popular: Mala-D, Mala-N
Saheli / Centchroman: A non-steroidal oral contraceptive developed at CDRI, Lucknow. Taken once a week. Contains centchroman — a SERM (selective estrogen receptor modulator)
Injectables: Depo-Provera (DMPA) — injected every 3 months. Contains progestogen only
Implants: Norplant — small rods implanted under the skin of the upper arm. Release progestogen for 3–5 years
Emergency contraceptive pills: Taken within 72 hours of unprotected coitus. High-dose progestogen (Levonorgestrel). NOT for regular use
Surgical Methods (Sterilisation)
Surgical sterilisation involves blocking the gamete transport pathway. Vasectomy (cutting vas deferens) in males and tubectomy (cutting/tying fallopian tubes) in females. Terminal method — meant for couples who do not want any more children.
Surgical methods are the most effective contraceptive methods (nearly 100%) but are essentially irreversible (reversal surgery exists but has low success rates). They are recommended for couples who have completed their families.
Small part of vas deferens is removed/tied
Small part of fallopian tube is removed/tied
Prevents sperm from reaching semen
Prevents egg from reaching uterus
Done under local anaesthesia
Done under general or local anaesthesia
Simpler, quicker procedure (~15 min)
More invasive, requires abdominal access
Does NOT affect hormone production — testosterone still produced
Does NOT affect hormone production — estrogen/progesterone still produced
Sperm are still produced but reabsorbed
Ovulation still occurs but egg degenerates
Both procedures block gamete transport — they do NOT affect hormone production or sexual drive
Both are nearly 100% effective but essentially irreversible
Surgical methods are also called sterilisation
These are terminal methods — recommended only when family is complete
The Ideal Contraceptive
NCERT defines an ideal contraceptive as one that is user-friendly, easily available, effective, reversible, with no or minimal side effects, and does not interfere with sexual drive or coitus.
No single contraceptive method is perfect. NCERT describes the ideal contraceptive as one that meets ALL of the following criteria. In reality, every method falls short in at least one area.
Should be user-friendly — easy to use without medical training
Should be easily available — no prescription or hospital visit needed
Should be effective — high success rate in preventing pregnancy
Should be reversible — fertility returns after stopping use
Should have no or negligible side effects
Should NOT interfere with sexual drive, desire, or the sexual act
Quick recall
Which contraceptive method provides protection against both pregnancy and STDs?
Condoms (male and female) — the ONLY method that provides dual protection. No other method (pills, IUDs, surgical) protects against STDs.
NEET Master Table: Natural (rhythm/withdrawal/LAM) → Barrier (condoms/diaphragm) → IUDs (CuT/LNG-20) → Hormonal (pills/injectables) → Surgical (vasectomy/tubectomy). Effectiveness increases left to right. Reversibility decreases left to right.
Sexually Transmitted Diseases (STDs)
STDs (also called STIs or VDs or RTIs) are infections transmitted through sexual contact. Bacterial: gonorrhoea (Neisseria), syphilis (Treponema), chlamydiasis (Chlamydia). Viral: AIDS (HIV), genital herpes (HSV), hepatitis B (HBV), genital warts (HPV). Prevention: condoms, avoiding multiple partners, early detection and treatment.
STD Prevention = Condoms + Monogamy + Early Detection
Bacterial STDs
Bacterial STDs are caused by bacteria and are generally curable with antibiotics if detected early. The three important ones for NEET are gonorrhoea (Neisseria gonorrhoeae), syphilis (Treponema pallidum), and chlamydiasis (Chlamydia trachomatis).
Bacterial STDs are the curable ones — they respond to antibiotic treatment. However, if left untreated, they can cause serious complications including infertility, PID (pelvic inflammatory disease), and even organ damage. The three NEET-important bacterial STDs each have a distinctive causative organism.
Gonorrhoea: Caused by *Neisseria gonorrhoeae* (a Gram-negative diplococcus). Symptoms: burning urination, pus discharge. Affects urethra, cervix, rectum
Syphilis: Caused by *Treponema pallidum* (a spirochete bacterium). Progresses in 3 stages — primary (chancre), secondary (skin rashes), tertiary (organ damage). Can cross placenta → congenital syphilis
Chlamydiasis: Caused by *Chlamydia trachomatis*. Often called the 'silent STD' because many people are asymptomatic. Most common bacterial STD worldwide
All three are treatable with antibiotics if caught early
Untreated bacterial STDs can lead to PID (Pelvic Inflammatory Disease) → infertility in females
Viral STDs
Viral STDs are caused by viruses and are generally NOT curable — only manageable. AIDS (HIV), genital herpes (Herpes simplex virus), hepatitis B (HBV), and genital warts (HPV) are the key ones.
Unlike bacterial STDs, viral STDs are incurable — there is no antibiotic that kills viruses inside cells. Treatment can only manage symptoms and slow disease progression. This makes prevention absolutely critical.
AIDS: Caused by HIV (Human Immunodeficiency Virus) — a retrovirus. Destroys CD4⁺ T-helper cells → immune collapse. Transmitted through sexual contact, blood, and placenta
Genital herpes: Caused by Herpes simplex virus type 2 (HSV-2). Causes painful blisters on genitalia. Lifelong infection with periodic outbreaks
Hepatitis B: Caused by HBV (Hepatitis B virus). Attacks the liver → cirrhosis, liver cancer. Vaccine available (part of universal immunisation)
Genital warts: Caused by HPV (Human Papillomavirus). Certain strains (HPV 16, 18) linked to cervical cancer. HPV vaccine available
HIV and Hepatitis B can also spread through sharing needles, blood transfusion, and mother-to-child (not just sexual contact)
Caused by bacteria
Caused by viruses
Curable with antibiotics
Not curable — only manageable
Gonorrhoea, Syphilis, Chlamydiasis
AIDS, Genital herpes, Hepatitis B, Genital warts
Generally do not cross placenta (except syphilis)
HIV and HBV can cross placenta
No vaccine available
Vaccines for Hepatitis B and HPV available
STD Prevention
Prevention is the only sure way to avoid STDs, especially viral ones. Key measures: condom use, avoiding multiple partners, early detection through lab tests, and avoiding sharing needles.
Since viral STDs are incurable and bacterial STDs can cause irreversible damage if caught late, prevention is the most important strategy. NCERT emphasizes a combination of behavioural and medical measures.
Use condoms during every sexual act — the single most effective prevention method for STDs
Avoid sex with unknown/multiple partners — monogamy drastically reduces risk
Get tested if there is any doubt — early detection prevents complications and transmission
Avoid sharing needles and ensure use of disposable syringes
Blood screening before transfusion — mandatory for HIV, HBV
Infected persons must inform their partners to prevent further spread
Timely treatment of bacterial STDs prevents PID and infertility
Quick recall
Which is the only contraceptive method that also prevents STDs?
Condoms (male and female). Pills, IUDs, and surgical methods prevent pregnancy but NOT STDs. This is a NEET classic.
Infertility is the inability to conceive after one year of unprotected intercourse. Causes include blocked tubes, low sperm count, hormonal imbalance, etc. ART includes IVF-ET (in vitro fertilisation and embryo transfer), ZIFT, GIFT, ICSI, AI (artificial insemination), and surrogacy. IVF babies are popularly called 'test-tube babies'.
IVF-ET: Ovum + Sperm in vitro Zygote lab culture Embryo (8-cell) transfer Uterus
Infertility
Infertility affects about 10-15% of couples. Causes can be in males (low sperm count, erectile dysfunction), females (blocked fallopian tubes, anovulation, endometriosis), or both. Diagnosis involves detailed medical history, physical examination, and lab tests.
A couple is considered infertile if they are unable to produce children even after unprotected sexual intercourse over a period of time (typically 1 year). Infertility is NOT the same as sterility — infertility may be treatable, while sterility is permanent inability to reproduce.
Infertility can be due to male factors (~40%): low sperm count (oligospermia), no sperm (azoospermia), poor motility (asthenospermia), erectile dysfunction
Can be due to female factors (~40%): blocked fallopian tubes, failure to ovulate (anovulation), endometriosis, uterine fibroids
Can be due to both partners or unexplained (~20%)
Hormonal imbalances in either sex can cause infertility
Physical, congenital, immunological, and even psychological factors can contribute
Diagnosis requires examination of both partners — not just the female
Artificial Insemination (AI/IUI)
In artificial insemination, semen collected from the husband or a healthy donor is artificially introduced into the vagina or uterus (IUI = intrauterine insemination) at the time of ovulation.
Artificial insemination (AI) is the simplest ART technique. Semen is collected from the male partner (or a donor if needed), processed in the lab to select the best sperm, and then artificially introduced into the female reproductive tract — either in the vagina or directly into the uterus (called IUI — intrauterine insemination).
Used when the male partner has low sperm count or poor sperm motility but sperm are functional
Semen can be from husband or a healthy donor (in case of severe male infertility)
Semen is processed to concentrate healthy, motile sperm
Introduced into the vagina or directly into the uterus (IUI)
Timing is critical — done around ovulation for maximum success
Simpler and cheaper than IVF — first line of treatment for mild male infertility
IVF-ET
In Vitro Fertilisation and Embryo Transfer (IVF-ET) involves fertilising the egg with sperm outside the body (in a lab dish/test tube), culturing the embryo to 8-cell stage, and transferring it into the uterus or fallopian tube.
IVF (In Vitro Fertilisation) is the most well-known ART procedure. 'In vitro' means 'in glass' — fertilisation happens in a laboratory dish, not inside the body. The resulting embryo is cultured to the 8-cell stage (blastomere) and then transferred into the female reproductive tract.
Step 1: Hormonal stimulation of the female to produce multiple eggs (superovulation)
Step 2: Eggs (ova) are surgically collected from the ovary
Step 3: Sperm collected from the male (or donor) are mixed with ova in lab conditions
Step 4: Fertilisation occurs in vitro → zygote forms → cultured to 8-cell stage (blastomere)
Step 5: Embryo transferred to the female reproductive tract
If embryo transferred to uterus → called IVF-ET (Embryo Transfer)
If embryo transferred to fallopian tube → called ZIFT (Zygote Intra Fallopian Transfer)
First IVF baby: Louise Joy Brown (1978, UK). First Indian IVF baby: Durga (also called Kanupriya Agarwal, 1978, Kolkata)
ZIFT, GIFT & ICSI
ZIFT transfers the zygote/early embryo into the fallopian tube. GIFT transfers the ovum and sperm directly into the fallopian tube (fertilisation happens in vivo). ICSI injects a single sperm directly into the ovum — used for severe male infertility.
ZIFT, GIFT, and ICSI are specialised ART techniques used when standard IVF or AI is not suitable. Each has a specific indication based on the nature of infertility.
ZIFT (Zygote Intra Fallopian Transfer): Zygote or early embryo (up to 8-cell stage) is transferred into the fallopian tube. Requires at least one functional tube
GIFT (Gamete Intra Fallopian Transfer): Collected ovum + sperm (gametes, NOT embryo) are transferred together into the fallopian tube. Fertilisation occurs IN VIVO (inside the body)
ICSI (Intra Cytoplasmic Sperm Injection): A single sperm is directly injected into the ovum cytoplasm using a micromanipulator. Used for severe male infertility (very low count or poor motility)
GIFT is the only ART where fertilisation is in vivo (inside the body) — all others involve in vitro fertilisation
After ICSI, the fertilised egg is cultured and transferred like in IVF
Transfers zygote/embryo
Transfers unfertilised gametes (ovum + sperm)
Fertilisation is in vitro (lab)
Fertilisation is in vivo (in fallopian tube)
Embryo at 8-cell stage transferred
Ovum and sperm transferred together
Transferred to fallopian tube
Transferred to fallopian tube
Needs lab fertilisation step
No lab fertilisation — more 'natural'
Surrogacy & Ethical/Legal Issues
Surrogacy involves transferring an embryo into the uterus of another woman (surrogate mother) who carries and delivers the baby. Raises legal, ethical, and social issues. India regulated surrogacy through the Surrogacy (Regulation) Act, 2021.
In some cases, a woman cannot carry a pregnancy due to uterine problems. The couple's embryo (from IVF) can be transferred into the uterus of another woman — the surrogate mother — who carries and delivers the baby. The genetic parents are the couple whose gametes were used.
Surrogate mother: Carries and delivers the baby but may NOT be the genetic mother
The embryo is formed from the gametes of the biological couple (or donors)
Surrogacy is used when the woman has a non-functional or absent uterus but functional ovaries
India's Surrogacy (Regulation) Act, 2021: Only altruistic surrogacy (no commercial payment) is legal. Surrogate must be a close relative
Commercial surrogacy (paying a woman to be a surrogate) is banned in India
Ethical concerns: exploitation of poor women, commodification of children, legal disputes over parentage
NCERT does not go deep into legal details of surrogacy, but questions about who the genetic parents are (gamete donors vs surrogate) have appeared in NEET. The surrogate is NOT the genetic mother if the embryo came from the couple's gametes.
Medical Termination of Pregnancy & Amniocentesis
MTP (Medical Termination of Pregnancy) is the intentional termination of pregnancy before full term. Legal in India up to 20 weeks (24 weeks in special cases, MTP Amendment Act 2021). Amniocentesis is a prenatal diagnostic technique to detect chromosomal and genetic disorders in the foetus, but its misuse for sex determination led to the PCPNDT Act (1994) banning sex-selective abortions.
MTP is the deliberate termination of pregnancy. Legalised in India by the MTP Act (1971). Safe during the first trimester (up to 12 weeks). Government legalized it to prevent unsafe, illegal abortions that kill thousands of women annually.
Medical Termination of Pregnancy (MTP) is the intentional ending of a pregnancy before the foetus can survive independently. It is also called induced abortion. In India, the MTP Act (1971) was passed to legalise and regulate abortions to prevent deaths from unsafe, backstreet abortions.
MTP Act passed in India in 1971, amended in 2021 (MTP Amendment Act)
MTP is safest in the first trimester (up to 12 weeks of pregnancy)
Legal limit: up to 20 weeks with one doctor's opinion; up to 24 weeks for special categories (rape survivors, minors, change in marital status) with two doctors' opinions (2021 amendment)
MTP is performed when: pregnancy is from rape/contraceptive failure, foetus has serious genetic defects, continuation endangers mother's life
MTP should NEVER be used as a contraceptive method — it carries medical risks
Must be performed only by registered medical practitioners at government-approved centres
When is MTP Justified?
MTP is legally justified on medical grounds (risk to mother's health), humanitarian grounds (pregnancy due to rape), eugenic grounds (genetic defects in foetus), and contraceptive failure.
MTP is not 'abortion on demand.' The law specifies clear conditions under which it is permitted. These fall under three broad categories: medical, humanitarian, and eugenic (genetic) grounds.
Medical grounds: Continuation of pregnancy risks the life of the mother or causes grave injury to her physical or mental health
Humanitarian grounds: Pregnancy resulting from rape or sexual assault
Eugenic grounds: Substantial risk that the child would be born with serious physical or mental abnormalities (detected through prenatal diagnosis)
Contraceptive failure: If pregnancy occurs despite using contraceptives (e.g., failed IUD, condom breakage)
MTP is NEVER legal for sex selection — this is explicitly banned under PCPNDT Act
Quick recall
Can MTP be used to abort a female foetus if the family wants a male child?
Absolutely NOT. This is a criminal offence under the PCPNDT Act (1994). MTP for sex selection is illegal in India. Doctors who perform sex-selective abortions face imprisonment and heavy fines.
Amniocentesis
Amniocentesis is a prenatal diagnostic technique where amniotic fluid is extracted (containing foetal cells) and analysed for chromosomal abnormalities, metabolic disorders, and genetic defects. Performed around 15-16 weeks of pregnancy.
Amniocentesis is a medical procedure in which a small amount of amniotic fluid is withdrawn from the amniotic sac surrounding the foetus using a long needle (guided by ultrasound). This fluid contains foetal cells that have been shed — these cells are cultured and their chromosomes are analysed (karyotyping).
Performed at 15–16 weeks of gestation (early second trimester)
A needle is inserted through the mother's abdomen into the amniotic sac (under ultrasound guidance)
Can detect: Down syndrome (trisomy 21), Turner syndrome (45,X), Klinefelter syndrome (47,XXY), and other chromosomal abnormalities
Also detects some metabolic disorders and neural tube defects (via alpha-fetoprotein levels)
The same technique can reveal the sex of the foetus — which led to its widespread misuse
PCPNDT Act
The Pre-Conception and Pre-Natal Diagnostic Techniques (PCPNDT) Act was passed in 1994 (amended 2003) to ban the use of prenatal diagnostic techniques for sex determination. Violation is a criminal offence with imprisonment and fines.
The widespread misuse of amniocentesis and ultrasound for determining foetal sex — followed by abortion of female foetuses — led to a dangerously skewed sex ratio in India. To combat this, the government enacted the PCPNDT Act in 1994 (amended in 2003 to include pre-conception sex selection techniques).
Full name: Pre-Conception and Pre-Natal Diagnostic Techniques (Prohibition of Sex Selection) Act, 1994
Amended in 2003 to also cover pre-conception sex selection (like sperm sorting)
Bans the use of amniocentesis, ultrasound, or any technique for sex determination of the foetus
Revealing the sex of the foetus to parents is a criminal offence — punishable with imprisonment (up to 5 years) and fine (up to Rs 1 lakh)
All diagnostic centres must be registered and display a board: 'Sex determination is prohibited here'
India's sex ratio at birth: 943 females per 1000 males (2011 census) — improving but still skewed
The PCPNDT Act is one of the most socially important topics in NEET Biology. Questions often test: (1) What is amniocentesis? (2) Why is it banned for sex determination? (3) What is the PCPNDT Act? (4) What is India's sex ratio? Expect 1-2 questions from this sub-topic alone.