GUIDE
Your baby is the size of a grape — and has officially graduated from embryo to fetus.
This week marks a significant developmental milestone. The embryonic period — when all major organs and structures were being established — is ending, and the fetal period is beginning. From now on, the focus shifts from organ formation to growth and maturation. The heart is fully formed with four chambers, tiny fingerprints are starting to take shape, and the tail from earlier weeks has disappeared.
Be prepared from day one
Your baby is about the size of a grape — roughly 22 to 30 millimeters from crown to rump, or just over an inch. This week, the developing organism officially transitions from "embryo" to "fetus," which signals that all major organ systems have been established and the focus now shifts to growth and refinement.
The heart is now fully formed with four distinct chambers — two atria and two ventricles — beating at about 140 to 170 beats per minute. The heart valves are developing, and the circulatory system is becoming more sophisticated. The heart rate is near its peak this week and will gradually slow slightly as pregnancy progresses.
Fingerprints are beginning to form as the skin on the tiny fingertips develops characteristic ridge patterns. The fingers and toes are now distinct — the webbing between them that was present last week is disappearing. The embryonic tail has been fully absorbed into the body. The face is looking more recognizably human: the eyes are more developed (though the eyelids are fused shut), the nose is more prominent, and the ears are closer to their final position on the head.
Internally, the liver, spleen, and gallbladder are developing. Reproductive organs are forming, though it is still too early to determine sex visually on ultrasound. The muscles are developing enough that the fetus is moving more actively — stretching, flexing, and even hiccupping, though you cannot feel any of it yet.
For a look at what happened last week, see our week 8 guide.
You may be at the peak of first-trimester misery — or you may be one of the lucky ones who feels relatively fine. Both experiences are normal. hCG levels are reaching their highest point around weeks 8-10, driving many of the symptoms that make the first trimester so challenging.
One symptom that surprises many people is nasal congestion. It has nothing to do with a cold — it is caused by increased blood volume, which causes the blood vessels in your nasal passages to swell. This "pregnancy rhinitis" can persist throughout pregnancy for some people and contributes to snoring, nosebleeds, and a general stuffy feeling.
Headaches are another common complaint at this stage. They can be triggered by hormonal changes, dehydration, caffeine reduction, fatigue, or stress. Acetaminophen (Tylenol) is considered safe during pregnancy for headache relief, while ibuprofen (Advil) and aspirin should generally be avoided. Staying hydrated and getting adequate rest are the best preventive measures. Constipation is also common right now, as progesterone continues to slow your digestive tract.
Your waistline may be starting to thicken, though you are not visibly pregnant to others yet. Your uterus has grown from the size of a fist to about the size of a grapefruit. This growth is happening entirely within your pelvis for now.
Every pregnancy is different. You may experience all, some, or none of these symptoms.
The priorities remain managing symptoms, maintaining hydration and nutrition, and preparing for upcoming screening decisions.
If you are in the thick of morning sickness, know that you are likely near the peak. For most people, nausea begins improving noticeably around weeks 12-14. Continue your management strategies — small frequent meals, ginger, vitamin B6, and prescription anti-nausea medication if recommended by your provider.
Dehydration is the biggest concern with persistent vomiting. Sip water, electrolyte drinks, or broth throughout the day. Popsicles, watermelon, and ice chips can help when drinking feels impossible. If you are unable to keep fluids down, your provider may recommend IV hydration.
If you have not already discussed screening with your provider, now is the time. NIPT (cell-free DNA screening) can be performed as early as 10 weeks, and the nuchal translucency scan is done between weeks 11 and 14. Understanding these options ahead of time helps you make a decision without feeling rushed.
Your breasts have likely grown by at least a cup size already, and they will continue to change. Invest in a few supportive, wire-free bras or bralettes. You do not need expensive maternity bras yet — just something that fits comfortably now. You will likely need different sizes at different stages.
When in doubt, call your provider. No question is too small during pregnancy.
Next week, your baby's vital organs will be functioning in their basic forms, teeth buds will be forming beneath the gums, and bones will begin to harden. You are now in the home stretch of the first trimester.
Next up: Week 10. If nausea is still significant, revisit our pregnancy nausea remedies. And if you are thinking about screening, our NIPT guide explains the most common first-trimester screening option. For a look at the full schedule of appointments ahead, see our prenatal visit schedule. If mood swings are catching you off guard, know that they are driven by the same hormonal shifts that are building your baby.
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.
