The way we track pregnancies is totally nuts. Some people go by the Gregorian calendar, others say that 4 weeks count as a month, still others have their own special way of charting. I'm going to try to explain tracking your months using the Gregorian calendar. This is the standard calendar that most people use.
LMP = Last menstrual period. This is the date that most maternity caregivers/websites go by. Regardless of when your last period was, they'll say that this date is two weeks before probable conception. Everyone's period is different, everyone's ovulation schedule is different, and nobody knows for sure when that sperm snuck into the egg, so this is what we'll go by for this lesson. Keep in mind that in America, we don't count the day until AFTER it occurs. You aren't 1 year old until you completed your entire first year of life and you aren't 1 day pregnant until the start of the second day.
If your LMP was on January 1 in a non-leap year, your calendar would be like this:
And you just continue this for every month. In this example, on April 15, this woman would be "14 w, 6 d" or "3 m, 15 d", depending on how she wanted to state how far along she was. On her due date (Oct 6th), she would be "40 w" or "9 m, 6 d".
Another thing people have problems figuring out is the difference between how many months you are compared to what month you're in. The easiest way I can think to explain it is that, for this woman during January (the first month of the year), she is IN her first month, but she doesn't turn 1 month until February 1st. You will always be IN the month before you TURN that month. When you are 5 months pregnant, you are in your 6th month, just like how your baby is in their first year for the 12 months before he/she turns 1.
Please leave a comment if you have any questions and I'll make sure to update this to include the answer.
