The second trimester — the one most moms say they love best Morning sickness eases · Energy comes back · Your bump starts to show

Week 16 sits squarely in the second trimester — the stretch many moms describe as the most enjoyable part of the whole pregnancy. Nausea fades for most, energy rebounds, the bump becomes visible, and the risk of miscarriage has dropped to very low.

This article draws on guidance from WHO [1], NHS [2], ACOG [3], and the Royal Thai College of Obstetricians and Gynaecologists [4] to help you make the most of this golden window.

Your baby at week 16

Your baby is about 11–12 centimeters from crown to rump and weighs around 100 grams — roughly the size of a medium avocado.

Key developments this week:

Facial muscles are starting to work — your baby can frown, squint, and move their mouth, even without meaning to
Legs are now longer than arms for the first time, with proportions beginning to look like a newborn's
Ears have moved into their final position — your baby can start hearing sounds from outside
Skin is still thin and translucent; blood vessels are visible beneath it
Circulatory system is running at full capacity
Urinary system — your baby is producing urine into the amniotic fluid
External genitalia are more defined — an ultrasound may be able to suggest the sex in some cases

Symptoms you may feel at week 16

According to ACOG [3], week 16 is typically when first-trimester symptoms ease off and you move into a more comfortable phase.

Positive changes

Morning sickness has faded or disappeared for most women
Energy is back after the exhaustion of the first trimester
More stable mood as hormone levels begin to level out
Appetite has returned — you may feel hungry more often
Hair and nails growing faster from pregnancy hormones

Symptoms that linger or newly appear

Back pain as your center of gravity shifts
Stuffy nose from increased blood flow to the nasal lining
Slight bleeding gums when brushing — a normal hormonal response
Skin darkening on the face (chloasma), around the nipples, and along the midline of the abdomen (linea nigra)
Round ligament pain — stretching sensations in the lower abdomen, normal as the uterus grows
Constipation as progesterone slows the digestive tract

Screening and routine checks at week 16

Per guidelines from the Royal Thai College of Obstetricians and Gynaecologists [4]:

Quad Test (second-trimester screening)

If you didn't have NT + Double Test or NIPT in the first trimester, weeks 15–20 is the right window for a Quad Test:

Measures AFP, hCG, uE3, and Inhibin-A in your blood
Estimates risk for Down syndrome, Trisomy 18, and neural tube defects
Sensitivity is around 80% — lower than NIPT
A screen result is not a diagnosis; high-risk results need follow-up testing

Amniocentesis

If screening shows elevated risk, or there are clinical indications:

Best performed at 15–20 weeks
A diagnostic test, not a screen — accuracy above 99%
Carries an estimated 0.1–0.3% risk of miscarriage
Discuss necessity and risk in detail with your obstetrician

Routine checks

Doppler fetal heart rate — normal range 120–160 bpm
Blood pressure — monitoring for pre-eclampsia
Urinalysis — glucose and protein
Weight — total gain should be around 3–5 kg from the start of pregnancy

Self-care at week 16

Nutrition

Per NHS [2] and WHO [1] guidance:

Add about 340 kcal/day in the second trimester
Protein — 71 g/day
Iron — 27 mg/day to prevent anemia
Calcium — 1,000 mg/day for your baby's bone development
DHA — 200–300 mg/day for brain and vision development
Fiber — more vegetables, fruit, and whole grains to ease constipation
Water — at least 8–10 glasses/day

Exercise and activity

The second trimester is the safest, most comfortable window for exercise:

30 minutes, 5 days a week per ACOG [3]
Walking, swimming, and prenatal yoga are all recommended
Start Kegel exercises — they strengthen the pelvic floor muscles
Practice sleeping on your left side — a habit that matters more in the third trimester
Avoid activities with a fall risk, hot tubs, saunas, and scuba diving

Activities that are now safe

Travel — the second trimester is the safest time to fly or take a long trip
Dental care — cleanings and routine work are safe and encouraged
Flu vaccine — recommended during pregnancy
Talk to your baby — the ears are working; familiar voices support development

Start thinking ahead to the third trimester

You're about halfway there — it's a good time to get some plans in place:

Childbirth preparation classes at your hospital — most run from weeks 24–28
Choose your delivery hospital if you haven't yet
Discuss parental leave with your employer
Start setting aside funds for newborn essentials

When to seek care immediately

Any vaginal bleeding
Severe abdominal pain or rhythmic cramping
Fluid leaking from the vagina
Severe headache or blurred vision — early signs of pre-eclampsia
Swollen face or hands — pre-eclampsia
Fever above 38.5°C (101.3°F) lasting more than 24 hours
Pain when urinating — possible urinary tract infection

Summary

Week 16 is a week many moms look back on fondly — symptoms are easing, your baby is growing fast, and you still have plenty of energy to prepare.

Care principles for this week:

Get your Quad Test if you haven't had NT + Double Test or NIPT
Increase calories by ~340 kcal/day with emphasis on iron, calcium, and DHA
Exercise regularly — 30 minutes, 5 days a week
Start Kegel exercises and practice sleeping on your left side
Talk to your baby — their ears are working, and familiar voices help development
Plan ahead — childbirth classes, delivery hospital, parental leave

Use this window well: rest, prepare, and start building that bond with the little one who can already hear your voice.

Pregnancy Week 16: Second Trimester Energy, Baby's Ears, and What to Do Next