Making a baby, let's start with the basics
This information is very general and applies to the boy-meets-girl way to make a baby.
Please seek specific advice from a health professional you trust and who can talk to your particular situation and circumstance.
Before trying to make a baby, I suggest you book an appointment (ideally a few months before) to see your doctor and work through the preconception checklist with them. Once you are ready, you need to stop using contraception e.g. stop condoms, withdrawal or the pill, or have your Mirena or Implanon removed or wait for the Depo injection to wear off.
OK, now let's talk about the baby-making basics.
To make a baby, you need
an egg (from mum)
some sperm (from dad)
a time and place for the egg and the sperm to meet
the formation of an embryo
a place for the embryo to grow (the uterus)
Women are born with all the eggs they will ever have. As women age, they have fewer eggs and it is harder to fall pregnant. Women ovulate (release an egg) only once per menstrual cycle, typically once every 4 weeks i.e. 13 times a year. Once released, the egg only survives for a matter of hours; we are not sure exactly how many hours, but perhaps 12-24. Physically, the easiest time for a woman to have babies is usually in the late teens/early 20s and it gets more difficult in the mid-late 30s and especially after 40. Psychologically and financially, that's a whole different matter!
Men continuously make sperm. Literally millions of them. Every day. The quality of the sperm and how well they move can be influenced by factors such as smoking, alcohol, drugs, diet, ageing and general fitness. Sperm can survive inside a woman for days, maybe even 5-7 days.
Egg + sperm need a time and place to meet:
In order for an egg to be fertilised by sperm, they have to have a time and a place to meet. Usually, this involves sex. Penis-in-vagina sex. Penis-in-vagina-until-he-comes sex. Now, it is possible for a sperm to make its way from the inner thigh to the vagina and thence to meet and fertilise an egg, but usually it's penis-in-vagina sex.
There are other techniques, such as IVF or home-made versions where the penis and vagina don't have to meet, but for those in a heterosexual relationship, sex is the cheapest and should be the most fun way to make a baby.
Timing is critical. Because the sperm can survive for days but the egg only for hours, it is recommended that couples have lots of sex, e.g. every couple of days for two weeks starting at the end of the period. If a woman has periods which are more than four weeks apart, this advice needs to be changed.
Not sure you understand ovulation? There are lots of ways to learn more, including Your Fertility website and fertility friend website and app.
The sperm has to make it through the wall of the egg in order for the egg to be fertilised, creating an embryo from which baby will grow. Sometimes this just doesn't happen on its own for all sorts of reasons and assistance in the form of IVF or donor sperm or eggs are needed.
Once the embryo is formed, it has to have a safe place to grow. Sometimes, it starts to grow in the tubes not the uterus, which is known as an ectopic pregnancy. This is potentially very dangerous as the tube is not big enough to grow a baby. Usually pain and bleeding 6-8 weeks after the last period will tell us that something is wrong.
Sometimes a uterus can be an unusual shape and this might have been present and not known about since birth, or the uterus may have become a bit bumpy, e.g. due to the growth of fibroids and this can impact upon successfully growing babies.
So, if couples have been trying to make a baby for many months* AND are having lots of penis-in-vagina-until-he-comes sex we will want to know 3 things:
Is she ovulating? We can order a hormone test that lets us know this, usually a Day 21 progesterone blood test.
Does she have a uterus, ovaries and tubes? Do they look ok? Could there be structural or other barriers to the egg and sperm meeting and baby having a safe place to grow? An ultrasound scan is usually done and sometimes a test to check the movement of fluid through the fallopian tubes also helps.
Is he making sperm, how many, do they look ok and move well? This involves a fresh sperm sample.
*How many is too "many months" varies. In a young couple (20s) with nothing in their history or on examination to make us think something could be getting in the way of making babies, 12-18 months is ok. In an older couple, particularly if she is over 35, 6-12 months would prompt further checks and if she is over 40, we typically start testing after 6 months. Please do understand that some couples make babies without much effort well into their late 40s. Just not many.