First trimester · Pregnancy week by week
Week 5 of pregnancy
Baby is the size of a sesame seed. About 0.05 inches.
By week 5, the embryo's heart begins beating. Pregnancy-induced hypertension affects Black women at 60% higher rates throughout pregnancy per ACOG Practice Bulletin 222 — establishing baseline blood pressure now matters. Source
What's happening with the baby
The embryo is now C-shaped, about the size of a sesame seed. The heart begins to beat (around 100–110 bpm). The neural tube starts to close (folic acid is critical). The chorion (which becomes the placenta) develops. Major organ systems begin forming.
What's happening for you
Many women begin to suspect pregnancy by now. Symptoms intensify: more pronounced fatigue, breast tenderness, mild nausea, heightened sense of smell, food aversions or cravings, mood swings due to rising hCG and progesterone.
Common (normal) symptoms this week
Fatigue, breast tenderness and tingling, mild nausea, food aversions, mood swings, frequent urination, light spotting that's not heavy.
Call your OB or 911 if
- Severe abdominal or one-sided pelvic pain with bleeding — possible ectopic pregnancy.
- Heavy vaginal bleeding (soaking a pad in an hour) with cramping.
- Fainting, severe dizziness, or shoulder-tip pain — ectopic with internal bleeding is an emergency.
- Fever over 101°F with chills or pelvic pain.
- Severe vomiting that prevents keeping any fluids down for 24+ hours (hyperemesis).
Why this week matters for Black families
The first trimester is when prenatal care begins, and the documented disparity in care begins here too. Black women are less likely to receive first-trimester prenatal care (78% vs. 88% for white women per the CDC). Establishing care early — before week 12 — is associated with lower complication rates across the rest of pregnancy. If you're newly pregnant and haven't been seen, call your OB or community health center this week. Adjunctive WIC eligibility means everyone enrolled in Medicaid is automatically eligible for WIC; that's a meaningful first-trimester decision (see WIC by state).
What to do this week
Schedule your first OB appointment if you haven't. Ask about chronic-condition baselines (blood pressure, blood sugar, thyroid). Continue prenatal vitamins. Avoid raw fish, deli meat, soft cheese, and alcohol. Stay hydrated.
References
- ACOG Practice Bulletin 222 — Gestational Hypertension and Preeclampsia. 2020.
- NIH Office on Women's Health: Pregnancy.
Last medically reviewed: .
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