Early Pregnancy Symptoms
Are you pregnant? One way to tell is to look for signs like tender breasts, fatigue, and nausea all of which can show up within weeks after conception.
Here's a look at the most common early symptoms of pregnancy, which is a time of great physical change. A woman may experience a variety of symptoms in early pregnancy, usually from around 6 weeks.
Conception and early pregnancy symptoms
Most conception and pregnancy research shows babies are conceived around two weeks before your next period would have been due - which is the same as saying conception begins two weeks after the start of your last normal period.
Unfortunately your body doesn't necessarily ring any bells or blow any whistles to let you know conception has taken place so it's likely you won't even know or feel the exact moment of conception.
Conception typically takes place when the sperm fertilises the egg in the fallopian tube and it then takes another six days for the newly fertilised egg to reach the uterus, and the mother is usually quite unaware of any physical changes taking place in her body.
It can take another six days for that fertilised egg - or newly conceived baby - to fully implant in the lining of the uterus and start 'interacting' with your body.
This 'interaction' involves your body providing the fertilised egg - also called a zygote - with nourishment from your blood stream. The newly fertilised egg will also produce hormones that move into your body to support the pregnancy.
Once the baby fully implants into your uterus, it prompts the release of a hormone called human gonadotrophin hormone (or HCG) into the blood stream.
Hormones and pregnancy symptoms
The HCG level starts very low, but the concentration rapidly increases in the following days to produce physical pregnancy signs in the woman.
HCG levels also provide the basis for detecting a pregnancy with a pregnancy test. This is why early pregnancy signs do not become noticeable until around the time the woman's next period would have been due - or 12 to 14 days after the moment of fertilisation.
In many cases, a woman will not notice any signs until one or two weeks after her period was due, which is technically when she is five or six weeks pregnant and the HCG level is sufficicently high enough to affect her body.
Women pregnant with twins or triplets may notice their pregnancy signs are more intense and noticed earlier on because they have higher levels of HCG in their system.
Other hormones beside HCG increase during pregnancy too, mainly progesterone and some oestrogen, which contribute to many of the early physical signs of pregnancy. These hormones are not tested for with pregnancy tests.
Early pregnancy hormone changes
Progesterone is a female hormone and the principal progestational hormone that is made mainly by the corpus luteum in the ovary and by the placenta.
Progesterone prepares the lining (endometrium) of the uterus (the womb) to receive and sustain the fertilized egg and is vital to allow a pregnancy to remain successful.
Progesterone rises pre-menstrually, but continues to rise further after the period is missed. This is why pre-menstrual feelings can be confused with early pregnancy signs.
Most women don't get pregnancy signs until after their period is missed and the hormones increase to levels that their body is not used to.
A few women do get pregnancy signs earlier than five or six weeks of pregnancy, especially if they have had a baby before, because their body is more sensitive to the hormones and they know they 'feel different' to being pre-menstrual.