Pregnancy Stages of Pregnancy Week by Week Pregnancy Week 2 Read about how your baby's journey begins in week two including ovulation and fertilization. By Parents Editors Parents Editors The Parents Editors byline means there is an experienced group of editors and journalists behind the scenes of the article. Learn more about the Parents team, our core values, and editorial guidelines. our editorial guidelines Updated on May 17, 2022 Share Tweet Pin Email How Big is Baby? Your due date will be calculated from the first day of your last menstrual period. Conception occurs about two weeks from this day, and that's when you're truly considered pregnant. In just 40 short weeks, your baby will grow from the size of a tiny seed to the size of a plump watermelon. Baby's Length: 0.00in.Baby's Weight: 0.00oz. Mom's Changing Body Is it official yet? Not quite—but be assured that your body's got those baby-making mechanics well under way. After fertilization, your ovaries start ramping up the production of progesterone, a hormone that prepares your uterus to host the newly fertilized egg, or zygote, that will live there for the next 38 weeks or so. SEBASTIAN KAULITZKI/SCIENCE PHOTO LIBRARY Baby's Development So far your baby doesn't exist, but this is the week you ovulate. Your ovary releases a ripened egg (ovum) into your fallopian tube, where it will patiently await the sperm that have survived the 6- to 8-inch trek through your cervix and uterus. While 75 to 900 million sperm embark on this journey, less than a thousand actually make it past your cervix—and only one lucky swimmer will have the honor of penetrating the egg at the moment of conception. Read More Weekly Tip Right now, you're just dying to find out: Am I pregnant or not? Unfortunately, you'll need to stick it out a bit longer. About four days after your egg is fertilized, it begins producing a hormone called human chorionic gonadotropin (HCG), which pregnancy tests can detect in about another week—first in your blood (via a test at your doctor's office) and then in your urine (which an at-home screening would spot). PeopleImages/Getty Images Week 2 Ultrasound There's no ultrasound image of your baby-to-be for weeks 1 and 2. While your health care provider counts these two weeks toward your due date, you aren't really pregnant. Confused? Your pregnancy due date is calculated using the first day of your last menstrual period (LMP). Obviously you weren't pregnant at that time, but it's the best reference your health care provider has for estimating baby's arrival day (until you get an ultrasound, which may provide a more accurate due date). Read More Watch Baby's Growth This Week's To-Do List Reduce your caffeine intake.Read More Talk to your doctor about safe medications during pregnancy.Read More Eat a healthy, balanced diet.Read More Don't overdo it when you exercise.Read More This Week's FAQs What can I do to increase my odds of getting pregnant? Must-Reads Why I Decided to Do Genetic Screening Before Trying to Get Pregnant At-Home Fertility Tests and Treatments: Understanding the Pros and Cons How to Find a Sperm Donor — And Choose a Good One How Long Does Ovulation Last? Was this page helpful? Thanks for your feedback! Tell us why! Other Submit