18 Weeks Pregnant

You’re in the second trimester and your baby is about the size of a sweet potato. Here’s how your baby is developing, what you might feel, and the check-ups to plan this week.

Reviewed against ACOG & WHO guidance Updated 25 September 2026
Baby is about the size of
A sweet potato (shakarkandi)
Length ~14.2 cmWeight ~190 gTrimester 2Month 5

Sizes are averages; from week 20 length is measured head to heel. Not sure which week you’re in? Calculate it.

Your baby at 18 weeks

The ears have moved into position and the baby may begin to hear sounds – your heartbeat, your digestion and muffled voices. Nerves are being coated with myelin. Yawns and hiccups are common.

Your body at 18 weeks

You may feel dizzy when standing quickly as blood pressure is naturally lower in mid-pregnancy. Leg cramps, especially at night, can start.

Common symptoms this week

  • Dizziness
  • Leg cramps
  • Movements more noticeable

Tips & to-do list

  • The anomaly (Level-II / TIFFA) scan is due between 18 and 22 weeks.
  • Stretch your calves before bed.
  • Note: in India, prenatal sex determination is illegal under the PCPNDT Act – scan centres will not disclose the baby’s sex.

Check-ups and tests around this week

  • Quadruple marker test if first-trimester screening was missed (15–20 weeks)
  • Anomaly / Level-II / TIFFA scan (18–22 weeks)

Week 18 at a glance

At 18 weeks
TrimesterSecond trimester
Pregnancy monthMonth 5 of 9
Weeks to due date22 weeks
Days pregnant126–132 days
Progress45% of 40 weeks

When to call your doctor

Contact your doctor or go to hospital straight away if you notice:

  • Any vaginal bleeding or fluid leak
  • Regular tightenings or period-like cramps before 37 weeks
  • Severe headache, blurred vision or sudden swelling of face and hands
  • Fever, or pain while urinating

Questions about 18 weeks pregnant

How many months is 18 weeks pregnant?

18 weeks pregnant falls in month 5 of pregnancy, in the second trimester. For medical purposes, weeks and days are more precise than months.

How big is my baby at 18 weeks?

At 18 weeks your baby is about the size of a sweet potato (shakarkandi) – roughly ~14.2 cm long and weighing about ~190 g.

Is it normal to have no symptoms at 18 weeks?

Yes. Every pregnancy is different, and symptoms come and go. Feeling well is not a sign that something is wrong. If you have concerns, or notice any warning signs listed on this page, contact your doctor.

Jump to any week

Medical disclaimer: The results and information on this page are estimates for general education only. They are not a diagnosis and do not replace advice from your gynaecologist, obstetrician or midwife. If you have pain, bleeding, reduced baby movements or feel unwell, contact your doctor or call 108 immediately. Read the full disclaimer.

Written by the Pregnancy Calculator editorial team. Based on published obstetric guidance (ACOG, WHO, MoHFW India, FOGSI). Last updated . How we create content.