The weeks of pregnancy are always counted from the first day of your last menstrual period (or LMP). In other words, the counting starts from two weeks before you conceive. This method has become standard practice because relatively few women can actually pinpoint the day of conception - but most can recall their last period.
At four weeks after your last period (two weeks after conception), you may find that:
• Your period does not start - although you may get some mild cramps, your breasts may feel heavy and full, and your nipples may be tingly or sensitive;
• You go off things like coffee or alcohol;
• There's an odd metallic taste in your mouth;
• You may find you produce more saliva;
• You start to feel sick (See Your pregnancy - 0-12 weeks/morning sickness for tips on how to cope). At this point a home pregnancy test may give a positive result.
At seven weeks since your last period (five weeks after conception):
• You are even more likely to be feeling sick;
• You may feel very tired. This is probably a reaction to rising levels of the sedative hormone progesterone;
• You may also find that you need to go to the toilet more often because your uterus is getting bigger and is pressing against your bladder;
• Constipation could become a problem. Try to drink at least two litres of water a day and eat more fruit and vegetables than usual.
In the first three months, you will probably find your rapidly growing baby is placing demands on your body which can leave you feeling overwhelmed with tiredness.
"At first I felt so sick, I couldn't eat anything. Now I've discovered that stuffing myself helps - bread, crackers, anything carbohydrate. And I just want to sleep all the time!" (Sally, 25, nine-and-a-half weeks pregnant.)