I had learnt this from my biology tuition teacher. Actually this topic is a previously topic during form 3 which was about human reproduction.
What I like to tell about is very useful for those who are plan to have babies or do not have babies. My teacher said if we, the teenagers are trying to ask our parents about such these things,just imagine what the dissapointed answers you will receive then you are fail in theory and you will try the 'experiment'.This why social problems among teenagers increasingly occur. parents don't give them chances to know everything about sex.
when teenagers like us ask..." papa, what is sex?"
papa whom maybe is reading the newspaper that time said..."go and ask your mom"
so, you go and ask the same question to your mom.
For those Malay teenagers,I'm so sure that you are commonly heard mom says like this "dah nak kahwin sangat ke???"
In this case,we need to change the way we think. It's not because you want learn about sex,ask about sex,it means you're the sex addicted person. please...be an open-minded when this topic is represented and is discussed.For parents,when children keep asking such that question,don't scold them. You must put aside your commitment as the mother and the father but create a condition whereas like a teacher teach his/her students.
I'm going to talk about menstrual cycle. Generally, menstrual cycle of a woman takes 28 days for another cycle. Menstrual can happen when no fertilisation occurs because the producing ovum after ovulation does not receives any sperms depends on its lifetime. At the same time,it will break down endometrium tissue since during the breakage,endometrium will pull along slightly blood vessel.That's why blood is flown out.
It differs when fertilisation occurs. The endometrium tissue will stay and sticked on the uterus wall and the uterus wall also keep its thickness.
The normal menstrual cycle usually occurs at day 1 until day 7. At day 7 until day 9 is the time when level of fertilisation occurs are soooooo minor.
Then,in day 14 we known as fertile phase. Fertile phase means the best level for fertilisation can occur (1.best time to have sexual intercoarse of a married couple and plan to have babies. 2.best time of union between ovum and sperm). 2 days before we achieve this day 14 in which is day 12, there is highly chances for fertilisation can occur. This situation can be occur after it reaches day 14. This highly chances can stay as long until day 20. Then, day 21 will be confronted same situation at day 7-9. Then,when there is no any sexual intercoarse is done,the menstrual starts to be cycled as usual.
* the days before menstrual occurs, ladies may have change of her mental,physical and emotion. This can lead them to be more sensitive and need people around her to understand her such give her attention. This occurs because of imbalanced hormoned and this situation had known as pre-menstrual syndrome (PMS).