Even if you know nothing about charting your cycles, anything you might have noticed about your body, along with any suspected dates of conception.beginning or ending of any pregnancy symptoms like nausea, vomiting, etc.– date of any pregnancy tests taken and results (most tests positive at about 4 weeks pregnancy)whether your baby’s heartbeat can be heard with a fetoscope (usually not until about 16-17 weeks if you’ve had a baby before, not until almost 20 weeks if you are a first-timer)when your baby’s heartbeat can be heard with a Doppler (as early as 9-10 weeks if you’ve had a baby before, a few weeks later for first-timers)measuring the height of your uterus, although this can vary from person to person and isn’t really accurate until about 20 weeks.
This means that accurate dating reduces your chance of having your labour induced because your baby is thought to be overdue.
It may also help you to avoid feeling disappointed towards the end of your pregnancy if you think your baby is late when he's not.
-how your uterus feels, from the outside (can feel it start to protrude out of the pubic bone at 12 weeks) and the inside (feels larger than normal by 7 weeks).-your report of any fluttering, or fetal movement.
The type of movement can help determine how far along you are as well, as kicks come later when bones are developing and getting stronger.
You may know when your LMP was, but not when you actually conceived.
If you do know the conception date, this is counted as day 14, not day one. You may need a second scan to check the first scan's findings. The dating scan will also show if you're expecting twins, triplets, or more. If you’re seeing a doctor or midwife with protocol about how many weeks they can let your pregnancy go (for many it isn’t much past 40 weeks), then you don’t want to take the chance that your due date is incorrect.You could unnecessarily face pressure about induction, or other issues that concern doctors about “postdate” pregnancies.If your cycle is irregular or you've recently been on the pill, working out the date from your LMP probably won't work. If the scan date differs from your period dates, the scan date will be used.