They consider your LMP (Last Monthly Period) to be the starting day of your last period, they track the 40 weeks of pregnancy from that, but no, it's not the actually day where you ovulated and got pregnant. You usually ovulate about 2 weeks AFTER your LMP so technically when you are "4 weeks pregnant" the baby is only 2 weeks.
No. Doctors (and other medical professionals) measure pregnancy in terms of LMP. If you are 7 1/2 weeks pregnant according to your doctor, you probably became pregnant about 5 weeks ago. This assumes you have the standard 28 day cycle, and became pregnant at mid cycle. LMP is not an accurate way to date a pregnancy. If you are in doubt, an ultrasound before the 18th week LMP is the most effective way to date your pregnancy.
Pregnancy is calculated from your last LMP, rather than the date of conception. So, if your last period was 7 weeks ago, you are 7 weeks pregnant. You actually conceived 5 weeks ago, around day 14 of your cycle.
GA is gestational age which is how far pregnant you are. LMP is last menstrual period, which is the date of the first day. EDD is estimated dte of delivery (40 weeks from the LMP) The EDD may be changed if the ultrasound gestational age differs from the age by LMP by a lot.
Last Menstrual Period
hCG levels in weeks from LMP (gestational age)* : 3 weeks LMP: 5 - 50 mIU/ml 4 weeks LMP: 5 - 426 mIU/ml 5 weeks LMP: 18 - 7,340...
Usually the doctors say the age is LMP. So if they say 15 weeks, it'd be about 13 weeks since conception.
ALL YOU HAVE TO DO IS FIGURE OUT THE FIRST DAY OF YOUR LMP (LAST MENSTRUAL PERIOD) AND THEN ADD 228 DAYS AND YOU SHOULD HAVE YOUR EDD.
Last Menstrual Period
Any counting of days regarding menstruation or fertility is always from the first day of your period - LMP is the day you started your last period, fertility window is from LMP - to days 9 thru 16 - the average cycle is 28 to 34 days beginning with LMP.
just add the days from your LMP to the current date. then round it up to weeks and days
== == hCG levels in weeks from LMP (gestational age)* : * 3 weeks LMP: 5 - 50 mIU/ml * 4 weeks LMP: 5 - 426 mIU/ml * 5 weeks LMP: 18 - 7,340 mIU/ml * 6 weeks LMP: 1,080 - 56,500 mIU/ml * 7 - 8 weeks LMP: 7, 650 - 229,000 mIU/ml * 9 - 12 weeks LMP: 25,700 - 288,000 mIU/ml * 13 - 16 weeks LMP: 13,300 - 254,000 mIU/ml * 17 - 24 weeks LMP: 4,060 - 165,400 mIU/ml * 25 - 40 weeks LMP: 3,640 - 117,000 mIU/ml * Non-pregnant females: