Week 4 · First trimester
4 weeks pregnant
For you
Some people notice no change at all this early; others notice tiredness, breast changes, nausea, spotting, or cramp-like sensations. Presence and intensity vary.
For baby or babies
Across the broad weeks 4–8 source range, implantation and early placental formation are part of the changing environment; development does not follow an app-perfect timetable.
Source: American College of Obstetricians and Gynecologists — How Your Fetus Grows During Pregnancy ↗
Development stage · Early formation
Across weeks 4–8, early structures including the brain, spine, and cardiac tissue begin to form.
Source: American College of Obstetricians and Gynecologists — How Your Fetus Grows During Pregnancy ↗
Week numbers are estimates, counted from the first day of the last period.
In the app this week
- Words you can show or say to your care team
- One clear ask for your supporter
- A prompt for the two of you
Free in the app for weeks 4–15.
About these sources
NHS — Week-by-week guide to pregnancy ↗
General education · United Kingdom public health source. The public guide supplies weekly pages from week 4 through week 41. UK care schedules and advice do not automatically apply elsewhere.
American College of Obstetricians and Gynecologists — How Your Fetus Grows During Pregnancy ↗
General development reference · United States professional organization. The source describes broad four-week development bands. Pace does not turn them into an individual assessment or claim that development follows an exact weekly schedule.
Source receipts reviewed 27 August 2026. General information that Pace, Please has summarised from the public sources named on this page. It is not medical advice, does not assess your pregnancy, and every pregnancy differs. Your care team and your own care plan come first.
If something feels wrong, contact your maternity team now. In an emergency, call your local emergency number.