The advanced method uses the Mittendorf-Williams rule, which is said to be more accurate since it takes more factors into account like race, weight and coffee consumption.

Egg Retrieval DateMaternal age1617181920212223242526272829303132333435363738394041424344454647484950RaceCaucasianNon-CaucasianPre-pregnancy heightftincmswitch to metricPre-pregnancy weightlbskgHigher educationNoYesAlcohol during pregnancyNoYesCups of coffee per day0123456789101112Incompetent cervixNoYesFirst pregnancyNoYesDES exposure in cervixNoYesHistory of miscarriageNoYesHistory of stillbirthNoYesBleedingNone1st Trimester1st & Other2nd, 3rd or BothPlacenta previaNoYesPlacental abruptionNoYesPremature rupture of membranesNoYesPregnancy induced hypertensionNoYesHow is my due date calculated?

Your due date is calculated by adding 280 days (40 weeks) to the first day of your last menstrual period (assuming a 28 day cycle).

Note that your menstrual period and ovulation are counted as the first two weeks of pregnancy. If you deliver on your due date, your baby is actually only 38 weeks old, not 40.

Please remember that your due date is only an estimate. Every pregnancy is unique and your baby will come when its ready. Be sure to talk to your health care provider about your due date.

On average only 5% of births take place exactly on the estimated due date. Most are born within a week either side of the estimated due date. A normal pregnancy can last anywhere between 38 and 42 weeks.

Each due date report contains the following data:

Due Dates for Multiples (Twins, Triplets, Quads)

Timeline of Significant Milestones in Embryo/Fetal Development

If you want to, you can view asample due date report.

Follow your babys development week by week in ourarticle series.

We have created a slew ofpregnancy calculators and toolsto help you through your pregnancy.