Reproductive Health Set-4

Q1. In an IVF cycle 4 mature oocytes are retrieved. Each oocyte has a 75% chance of fertilising and each resulting embryo implants independently with probability 24%. Assuming independence, the probability of at least one implantation is given by $1-(1-0.75\times 0.24)^4$. Its approximate value is:

Q2. Assume the number of primordial follicles follows $N(\text{age})=N_{20}e^{-k(\text{age}-20)}$. If $N_{20}=100000$ and $N_{30}=50000$, at what age will $N(\text{age})$ fall to $10000$ (approximately)?

Q3. A couple had unprotected intercourse on three consecutive days of a cycle. The probabilities of conception from a single act on those days are $0.05,\ 0.15,$ and $0.25$ respectively. Assuming independence between acts, the probability that conception occurred from at least one of these acts equals $1-(1-0.05)(1-0.15)(1-0.25)$. Its approximate value is:

Q4. Assertion (A): Levonorgestrel emergency contraceptive taken within 72 hours prevents pregnancy mainly by preventing or delaying ovulation.
Reason (R): Levonorgestrel emergency contraceptive works chiefly by disrupting implantation through altering endometrial receptivity.

Q5. In an IVF transfer two embryos are placed. Each embryo implants independently with probability $0.25$. If exactly one embryo implants the chance of a live birth from that implanted embryo is $0.95$; if both implant the probability that the pregnancy results in at least one live birth (due to higher prematurity risks) is $0.75$. What is the probability that the transfer yields at least one live birth?

Q6. A contraceptive method has a typical‑use failure rate of $2\%$ per year. Assuming failures in different years are independent, what is the probability that a couple using this method continuously will experience at least one contraceptive failure during a 2‑year period?

Q7. During a sexual act a male condom has a per‑act failure probability of $2\%$ and a combined oral contraceptive (COC) has a per‑act failure probability of $0.5\%$. Assuming independence of failures and that both methods are used simultaneously in the same act, what is the probability of pregnancy from that single act?

Q8. A couple with primary infertility has the following results: semen concentration $=8$ million/ml, progressive motility $=20\%$, ejaculate volume $=3$ ml; hysterosalpingography shows both fallopian tubes patent. Using the formula $TMCC=\text{concentration}\times\text{volume}\times\text{motility fraction}$, calculate the total motile sperm count and select the most appropriate next technique to maximise fertilisation probability while remaining as non‑invasive as possible.

Q9. Assertion (A): Insertion of a copper‑bearing intrauterine device (Cu‑IUD) commonly increases menstrual blood loss and can aggravate iron‑deficiency anemia.
Reason (R): Copper ions released by the IUD provoke a local endometrial inflammatory response and increase prostaglandin synthesis, which together increase endometrial vascularity and bleeding.

Q10. Assertion (A): Common broad‑spectrum antibiotics such as amoxicillin significantly reduce the effectiveness of combined oral contraceptives (COCs), increasing the risk of unintended pregnancy.
Reason (R): Broad‑spectrum antibiotics can disrupt intestinal microbiota and thereby reduce enterohepatic recycling of ethinylestradiol, potentially lowering its plasma concentration.

Q11. A contraceptive method has a failure probability of $p=0.02$ per menstrual cycle (assume independence between cycles). The probability that a woman becomes pregnant at least once in $12$ cycles is given by $1-(1-p)^{12}$. The approximate value of this probability is:

Q12. A 30-year-old woman has bilateral tubal blockage confirmed by hysterosalpingography; her husband’s semen analysis shows severe asthenozoospermia with a total motile sperm count of $0.8\times10^{6}$ per ejaculate. Which assisted reproductive technique most directly addresses both the tubal factor and the severe male factor to maximise their chance of conception?

Q13. A couple has had three consecutive first‑trimester miscarriages. The wife's karyotype is normal; the husband's karyotype reveals a balanced reciprocal translocation. To minimise the risk of further miscarriages or birth of a chromosomally unbalanced child while preserving genetic relation to both parents, the most appropriate reproductive option is:

Q14. Assertion (A): Use of an intrauterine device (IUD) increases the overall incidence of ectopic pregnancy in the population.
Reason (R): Although IUDs reduce the total number of pregnancies, when pregnancy does occur with an IUD in situ the relative proportion of those pregnancies that are ectopic is higher than in pregnancies without an IUD.
Choose the correct option:

Q15. Both partners are carriers of beta-thalassemia trait (autosomal recessive). They want a genetically related child who will not be affected by the disease and they categorically refuse pregnancy termination under any circumstance. Which reproductive strategy best fulfils their requirement while minimising the chance of having an affected child?