Trimester Symptom Guide
See which pregnancy symptoms and antenatal checks belong to your gestational week, with the signs that need same-day review.
About this tool
Trimester Symptom Guide
See which pregnancy symptoms and antenatal checks belong to your gestational week, with the signs that need same-day review.
The Trimester Symptom Guide maps a gestational week to the symptoms usually reported in that window and the antenatal checks usually offered around it. Gestational age is counted from the first day of the last menstrual period, trimesters split at 14w0d and 28w0d, and the estimated due date uses Naegele's rule of LMP plus 280 days. Enter a week from your scan report or work it out from your last period, and the timeline shows what is current, what is coming in the next four weeks, and which signs are never routine.
How to use Trimester Symptom Guide
- 1
Open Trimester Symptom Guide on AltFTool — it loads instantly in your browser.
- 2
Choose "I know my week" and enter completed weeks (0-44) plus extra days, or "Work it out from my last period" with the first day of your last period.
- 3
Read the gestational age card: trimester, estimated due date, days remaining and progress through 40 weeks.
- 4
Review "Commonly reported at N weeks", the antenatal checks around this point and the "Never wait on these" urgent-signs list; "Copy result" copies the week summary.
Why use Trimester Symptom Guide
Week-accurate, not vague
Every symptom carries the week range it usually spans, so nothing is listed out of its window.
Screening windows included
Dating scan, anomaly scan, glucose tolerance test, anti-D and Tdap timings sit alongside the symptoms.
Clear escalation line
Bleeding, reduced movements, severe headache and sudden swelling are flagged separately as urgent, never as normal.
Common use cases
- Checking at 20 weeks whether the anomaly scan window has opened and what to ask about at the appointment
- Working out why nausea has suddenly eased at 14 weeks and what typically replaces it
- Seeing which screening tests fall in the 24-28 week window so nothing is missed between visits
Frequently asked questions
When does each trimester start and end?
The first trimester runs from 0w0d to 13w6d, the second from 14w0d to 27w6d, and the third from 28w0d until birth. Weeks are counted from the first day of your last period, which is about two weeks before conception.
When will I feel the baby move?
Most people feel first movements, called quickening, between 16 and 22 weeks, typically around 18 to 20 weeks in a first pregnancy and a couple of weeks earlier in later ones. After 24 weeks any noticeable reduction in the usual pattern of movements should be reported the same day.
When does morning sickness usually stop?
Nausea most often starts around week 6, peaks near week 9, and settles between weeks 13 and 16 for the majority of pregnancies. Vomiting severe enough that you cannot keep fluids down needs medical review, as that may be hyperemesis rather than ordinary sickness.
Which pregnancy symptoms are not normal?
Vaginal bleeding, fluid leaking before 37 weeks, reduced fetal movements, a severe headache with visual changes or upper abdominal pain, sudden swelling of the face and hands, fever above 38 C, and regular painful tightenings before 37 weeks all need prompt assessment. Contact your midwife or maternity unit rather than waiting for the next scheduled appointment.