Friday, 28 August 2020

Fecundity : The rate of conception in human females per cycle

 

Q.1: What is the fertile period during  the entire  spell of menstrual   cycle. ?

The number   of fertile   days of a menstrual cycle is difficult to quantify. The sperms remain alive in the female genital   tract and are   capable     of fertilization for up to 5 days   after ejaculation. The egg appears to be capable of being fertilized for only about 24 hours .

In a recent study   amongst couples   actively trying to conceive   with hormone measurement   to determine the timing of ovulation it was learnt that the fertile   period lasted about six days ending on the day  of ovulation . However in a   woman with reasonably regular   menstrual cycle of about 28 day, day 10   to day 17  is considered   as fertile period . But  in women with irregular   period concluded that   fertile  period should be considered as day  7 to day   15 of menstrual cycle.

Q.2: What is the probability of conception   after one or multiple    acts of intercourse?

Ans:-The probability of  conception after single  act of intercourse is approximately 8%  conception rate has been calculated to be about  but if multiple acts it comes to 13%  per cycle    if intercourse occurs on average  every other    day . But  if it   occurs    only once  a week  the risk of  pregnancy is about 15% . Most  women who   have unprotected intercourse   on a single  occasion   therefore will  possibly not conceive.

Q.3: What is the risk of conception if there is only single act of coitus  in the entire cycle ( expected cycle -  day specific conception   rate i.e. Barrett  and Marshall study )?

Ans: The overall risk of pregnancy after a single act of unprotected   sex on any day of the cycle in 2-4%    and is highest in the days before and just after  ovulation  . There is no day of the menstrual cycles when there   can be certainly   that unprotected   sex would not result in   pregnancy although   the probability is negligible in the first 3 days of the cycle . Timing   of sexual    intercourse   in relation to ovulation   - effects   on the probability of conception   , survival of   the pregnancy    and sex of the baby , (Source : New   England    Journal   of medicine  Vol.333. )

Q. 4 .What is meant by fecundity?? Ans: A normal   fertile sexually active couple not using   contraception   has maximum monthly chance of conceiving    20-25%   .

Q.5 :  What is the spontaneous unavoidable loss of a fertilized zygote?? Will all fertilized human egg give birth to a live  baby ? What is the incidence   of post   fertilization preimplantation   wastage?

Ans: After  fertilization 25% of zygotes  do not  implant   and those  that implant a proportion   is lost before   a pregnancy  becomes  clinically  recognizable Thus  in 42%  cases no clinically recognizable   pregnancy results  even after  fertilization .Eight   per cent   of all clinically recognized  pregnancies are spontaneously lost even if  such cases had demonstrated gestational SAC in TVS.  .

Q.6: Then what is the exact relevance of emergency contraceptives?? Accordingly  prospect of EC within 120 hours  of intercourse  by interruption of the natural development of a fertilized ovum appears very low   and more so after a single  act of unprotected  intercourse. Therefore   in a vast   majority of cases EC addresses a theoretical or statistical   rather   than   an actual chance of   fertilization having occurred  and  lives  the women ‘s    apprehension of  unwanted    pregnancy  considerably.

Q.7: What is the Longevity of sperms ?

There is great individual variation between men and between individual sperm with the same men’s   ejaculate.

Q.  8: What is the rate of spermatogenesis ?? Scientists have shown that – sperm   counts and quality of sperm have  lowered in the recent   years. In normal   healthy men  spermatogenesis    occurs at the  rate 1,000 sperm   per second  from each   testis   and an ejaculate   of   3-5  usually  contains  350   million  sperms  though only one ova  need to be  fertilized. Sperms can remain   alive in cervical    mucus for   5-6  days depend on quality of cervical  mucus.

Q. 9: Frequency   of sexual intercourse  &  knowledge of fertile  period ?

WHO   in the early 1990 estimated that intercourse  takes place   over 42,000 million  times per years. This   means every second there 1,300 ejaculations with possible pregnancy  .Now with increase of population it seems that this may somewhere 2000 ejaculation in vagina per second with possible pregancy  . Different studies   have shown that sperm   can remain alive in female   genital    tract for about six days

Q.10: What is  Safe   period   in human   menstrual cycle? Ans:   Safe   period   in human   menstrual cycle has long    been debated. The whole   of the second week of 4 week long menstrual cycle is potentially fertile i.e.  days 7 to day 14 of cycle. Even sex during   menstruation    can lead   to conception  if by chance   ovulation   occurs on day 7 of cycle , though   this is rare but not  impossible  because sperm  can remain   alive for 5-6 days .

Q.11. What is  abortion rate ?

Abortion rate is defined as the number    of all types of abortions, per 1000  women   of childbearing  age. But    abortion ratio   is calculated  by dividing the number  of  abortions  performed   during a particular time   period  by the number   of live  births  over the  same  period.

Q. 12: What  is General Fertility Rate(GFR) ?

It is   the number of live   births per 1000 women in the  reproductive   age group  in a given years.


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