GUIDE
Your baby is the size of a lentil — and the heartbeat may be detectable on ultrasound this week.
This is a milestone week. The embryo's heart is beating at 100-160 beats per minute, fast enough to be picked up by a transvaginal ultrasound. Tiny limb buds are sprouting, facial features are beginning to form, and the brain is developing rapidly. For many pregnant people, this is also the week morning sickness shifts from mild to unmistakable.
Be prepared from day one
Your baby is about the size of a lentil — roughly 4 to 6 millimeters long, measured from crown to rump. Growth is happening at an astonishing pace; the embryo is now 10,000 times bigger than it was at conception.
The most exciting development this week is the heartbeat. The heart, which started as a simple tube, has begun to divide into chambers and is beating rhythmically — about 100 to 160 beats per minute. On a transvaginal ultrasound, this appears as a tiny, rapid flickering. Hearing or seeing your baby's heartbeat for the first time is one of the most emotional moments of early pregnancy.
Tiny limb buds have appeared — small paddle-shaped protrusions where the arms and legs will grow. The embryo also has a prominent tail (which will disappear as development continues) and an oversized head relative to its body, reflecting the rapid brain development underway. Dark spots are forming where the eyes will be, and small depressions mark the future ear canals. The mouth and jaw are taking initial shape.
Inside the embryo, the lungs, liver, and kidneys are beginning their earliest stages of formation. The intestines are starting to develop, and the appendix is already present.
For a look at what happened last week, see our week 5 guide.
For many pregnant people, week 6 is when symptoms become undeniable. The combination of skyrocketing hCG, rising progesterone, and increasing estrogen is affecting virtually every system in your body.
Nausea may be your dominant experience this week. It often intensifies from the mild queasiness of week 5 into more persistent waves that can last for hours. In severe cases, persistent vomiting may point to hyperemesis gravidarum, which requires medical attention. Some people find that certain smells — cooking meat, coffee, perfume — are now intolerable triggers. Food aversions can appear overnight: foods you loved last week may now make you gag. This is normal, frustrating, and temporary.
Fatigue continues to deepen. Your body is pouring resources into building the placenta, increasing blood volume, and supporting rapid embryonic growth. Your resting metabolic rate has increased, even though you are not doing anything differently. Many people describe first-trimester fatigue as unlike any tiredness they have experienced — a bone-deep exhaustion that sleep does not fully resolve.
You may notice that your clothes feel slightly tighter around the waist, even though you are not "showing" yet. This is bloating from progesterone slowing your digestive tract, not the uterus — which is still small and tucked deep in your pelvis. Your breasts, however, may already be noticeably larger and more tender.
Every pregnancy is different. You may experience all, some, or none of these symptoms.
Managing nausea and staying hydrated are the top priorities this week. Everything else is secondary to making sure you are eating enough and keeping fluids down.
Eat small, frequent meals every two to three hours — an empty stomach worsens nausea. Bland, starchy foods (crackers, toast, rice, bananas) are often better tolerated. Ginger tea or ginger candies may help. Vitamin B6 (25 mg three times daily) is a first-line treatment recommended by ACOG. Talk to your provider before starting any supplement.
Dehydration makes nausea worse, creating a vicious cycle. If plain water is hard to tolerate, try adding lemon, sipping on ginger ale, eating ice chips, or drinking electrolyte beverages. Popsicles can also help. Aim for small, frequent sips rather than large amounts at once.
Your first appointment (usually weeks 8-10) will include a full health history, physical exam, blood tests (blood type, Rh factor, CBC, infectious disease screening), urine tests, and often an ultrasound. Prepare a list of medications, family health history, and any questions you have.
Walking, swimming, prenatal yoga, and stationary cycling are excellent options. Exercise helps manage fatigue, improves mood, reduces constipation, and supports healthy weight gain. Even 20-30 minutes of moderate activity most days makes a difference.
When in doubt, call your provider. No question is too small during pregnancy.
Next week, your baby's brain will be developing at a remarkable rate, and facial features will become more defined. The arms and legs will start to grow longer and take shape.
Next up: Week 7. If morning sickness is making life difficult, our morning sickness guide and nausea remedies have detailed coping strategies. For a broader view of what the coming weeks hold, read our complete first trimester guide.
This guide is for informational purposes only and is not a substitute for professional medical advice. Always consult your healthcare provider with any questions about your pregnancy.
