While it’s true that due dates are a moving target of sorts (a reason why women joke it’s more like a due “month” than a due “date”), getting an accurate estimate of when you conceived – and when your baby is due – helps us provide the best quality prenatal care throughout your pregnancy.

How is a due date calculated?

If you’re participating in fertility treatments or know exactly when you conceived, your healthcare provider will work with that date to calculate your due date. More often, physicians use a “280-day rule” to calculate their patients’ due dates – using the first day of their menstrual cycle as Day 1 – stretching through a 10-lunar month long, full-term pregnancy expectation: your due date.

Calculating an accurate due date is trickier for women who don’t track their cycles, have irregular periods or who don’t ovulate regularly; in those cases, we use ultrasounds to help us gauge the due date, with standard fetal development measurements as our guide.

Due dates help us track maternal health and normal fetal development

Obviously, due dates are helpful for you and your family to better prepare for baby. However, we ultimately want to have a handle on your due date so we can better track your maternal health and your baby’s development via regularly scheduled prenatal visits.

In most cases, you’ll visit your OB and/or midwife every month, and more frequently towards the end of your third trimester. In the meantime, knowing your due date supports your pregnancy by allowing you to:

Choose the best time to tell extended family member and friends

The good news is you’re pregnant! The shakier news is that about 20% to 25% of conceptions end in miscarriage, largely the result of abnormal chromosomal or genetic issues. Most women choose to keep their pregnancy news to a close and trusted few for the first 12- to 15-weeks (the window when most miscarriages take place), waiting until the end of the first trimester to tell extended family and friend networks.

Listen for the heartbeat (around 8-weeks) and verify baby’s movements

Your baby’s movements won’t be felt by you until around 18- to 20-weeks, less time if you’re very thin, or you’ve been pregnant before. In the meantime, we’ll expect to hear the heartbeat around Week 8 with the Doppler.

Knowing where you are in your pregnancy helps us to know what’s normal – and what’s not so we don’t elicit undue alarm in either direction. If we feel confident about your due date – give or take a week or so – we’ll know what to listen and look for, when.

Choose from relevant screening and testing options

Throughout your pregnancy, we’ll also offer you prenatal screening or testing options, the majority of which test for certain chromosomal or genetic disorders, as well as tests that tell us how you and your baby are doing.

These tests are broken into four categories:due date

The spectrum of tests are offered at specific times throughout your pregnancy. If we don’t have an accurate due date, we risk faulty results – which doesn’t do you or baby any favors. Accurate results provide improved care and treatment options.

Enjoy a healthier pregnancy, quickly treating any potential conditions that arise

We’ll also test you to keep track of your general health, make suggestions around diet and lifestyle changes that will help most at that stage of pregnancy, monitor pregnancy symptoms and blood pressure to keep an eye out for preeclampsia, and we’ll test blood sugar levels to screen you for gestational diabetes. The healthier you are, the healthier your baby will be.

Know when to look for telltale labor signs

Did you know women can have Braxton Hicks (“practice contractions” that are not the same as labor contractions)? If you don’t know your due date, it’s easy to confuse Braxton-Hicks contractions with the real thing, especially during your first pregnancy.

On the flip side, signs of preterm labor are also important to distinguish, and if you think you’re 8-months pregnant, when you’re actually 6-months along, it makes a big difference in terms of your baby’s outcome if you go into labor.

Knowing your due date gives everyone a foundation from which we can assess pregnancy signs and symptoms.

Ready to receive an accurate due date and exceptional prenatal care throughout your pregnancy, labor and delivery? Schedule a consultation with a midwife or doctor at Overlake OB/GYN.