Week 1 of Your Pregnancy

A look at your body, your baby, and more

week 1 pregnancy highlights


Welcome to the very first week of your pregnancy. One thing: You aren’t actually pregnant yet.

Your healthcare provider calculates your due date from the first day of your last menstrual period (LMP). This means that the 40-week countdown really begins about two weeks before the sperm and the egg meet and start slowly transforming into a fetus.

If you’ve already taken a pregnancy test and spotted the telltale pink lines, you’re likely further along than you think. (Pregnancy registers on home tests on or about week 4.) Officially pregnant or not, this is still considered the first week of your first trimester.

Your Trimester: First trimester

Weeks to Go: 39

Verywell Checklist

  • Start taking prenatal vitamins.
  • Write down the date of your last two periods.
  • Quit smoking, drinking, and using any illegal drugs.

Symptoms This Week

Right now, your body is busy shedding your uterine lining, which holds last month’s unfertilized egg. As such, you’re experiencing the typical symptoms you’d normally feel when starting your period, including some bloating and mood changes due to fluctuating hormones. If all goes well, you won’t actually conceive until week 3.

Your Baby's Development

While there is no baby growing yet, your hormones are preparing another egg to be released for ovulation. Women with regular menstrual cycles ovulate about 10 to 20 days after the first day of their period; this timeframe dictates the best time to have sex to get pregnant.

Self-Care Tips

Now is the time to create the most hospitable and health-promoting environment for baby-to-be possible. For starters, begin taking 400 micrograms of folic acid every day. (The average American diet provides between 200 to 250 micrograms daily. However, pregnant women—and those trying to conceive—should consume 600 micrograms total, making 400 via supplement the optimal amount.)

Low levels of folic acid are linked to birth defects, including cleft lip and palate, and neural tube defects, such as spina bifida. “Taking in the correct amount prior to pregnancy and during the first trimester decreases the likelihood of these birth defects by 75 percent,” says Dr. Hill.

It’s not all about what you add to your routine, it’s also about what you take away. When trying to conceive, it’s more important than ever to avoiding alcohol, drugs, and tobacco products, including e-cigarettes. These habits can lead to birth defects, respiratory problems, low birth weightfetal alcohol syndrome, and other health issues.

A Word From Allison Hill, M.D., OB-GYN

“Taking in the correct amount [of folic acid] prior to pregnancy and during the first trimester decreases the likelihood of birth defects by 75 percent.”

At Your Doctor’s Office

If you have yet to visit your healthcare provider for a preconception appointment, do so now. Here, your doctor or midwife can fill you in on the possible safety implications of any prescription and over-the-counter medications or supplements you may be taking.

In addition, he or she can recommend a prenatal vitamin; review your medical and vaccine history; screen you for sexually transmitted infections; and give you a basic physical exam. This is also an opportunity to identify lifestyle, nutrition, exercise, and other personal habits that may impact your pregnancy.

“Think of your preconception visit as an opportunity for you and your healthcare provider to control the things that you can control in a pregnancy,” says Allison Hill, M.D., an OB-GYN and author of Your Pregnancy, Your Way and co-author of The Mommy Docs’ Ultimate Guide to Pregnancy and Birth. “This visit can increase your chances of having a healthy baby.”

Upcoming Doctor’s Visits

In most cases, you can wait to schedule your first prenatal visit between around eight and 12 weeks after your last menstrual period. First-timers may be surprised by the delay, but know that the best time to estimate gestational age with an ultrasound is actually between week 8 and week 13 of your pregnancy.

Schedule your first doctor's visit between eight and 12 weeks after your last menstrual period.

Taking a peek too soon (or too late) may result in an inaccurate due date estimation. If, however, you are at risk for early complications, such as an ectopic pregnancy, your healthcare practitioner may wish to see you sooner.

However, if you don’t trust your home pregnancy test, there’s a chance your healthcare provider may see you earlier to offer you a blood test. An in-office blood test can detect a pregnancy about six to eight days after ovulation.

Advice for Partners

Pregnancy is between partners, and that means both parties need to take care of their health and wellbeing. Before trying to conceive, it’s recommended that men be screened (and treated for) any possible sexually transmitted infections.

In addition, you can improve your reproductive health by limiting alcohol and quitting tobacco and illegal drug use. It’s been shown that men who drink excessively, smoke, or use drugs can experience problems with their sperm, thus making conception more difficult.

A Tip From Verywell

Partners can improve their reproductive health by limiting alcohol and quitting tobacco and illegal drug use.

Was this page helpful?
Article Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Oliver R. Embryology, Fertilization. StatPearls [Internet]. Published June 4, 2019.

  2. Wilcox AJ, Dunson D, Baird DD. The timing of the "fertile window" in the menstrual cycle: day specific estimates from a prospective studyBMJ. 2000;321(7271):1259–1262. doi:10.1136/bmj.321.7271.1259

  3. Czeizel AE, Bártfai Z, Bánhidy F. Primary prevention of neural-tube defects and some other congenital abnormalities by folic acid and multivitamins: history, missed opportunity and tasksTher Adv Drug Saf. 2011;2(4):173–188. doi:10.1177/2042098611411358

  4. Sharma R, Biedenharn KR, Fedor JM, Agarwal A. Lifestyle factors and reproductive health: taking control of your fertilityReprod Biol Endocrinol. 2013;11:66. Published 2013 Jul 16. doi:10.1186/1477-7827-11-66

  5. McLay JS, Izzati N, Pallivalapila AR, et al. Pregnancy, prescription medicines and the potential risk of herb-drug interactions: a cross-sectional surveyBMC Complement Altern Med. 2017;17(1):543. Published 2017 Dec 19. doi:10.1186/s12906-017-2052-1

  6. Taipale P, Hiilesmaa V. Predicting delivery date by ultrasound and last menstrual period in early gestation. Obstet Gynecol. 2001;97(2):189-94. doi: 10.1016/S0029-7844(00)01131-5

Additional Reading