Key Milestone Weeks in Pregnancy Second Trimester (Weeks 14–27)

Meconium is your baby’s first bowel movement, made up of materials they’ve ingested while in the womb—like amniotic fluid, skin cells, and mucus. It’s a thick, sticky, greenish-black substance that begins forming in the baby’s bowel during the second trimester, around 18 weeks. This is a normal part of foetal development and prepares the digestive system for functioning after birth. Meconium is usually passed after birth, but in some cases, it can be released into the amniotic fluid before delivery, which may require monitoring by your healthcare team.

At 18 weeks pregnant, the amount of weight you should gain depends on your pre-pregnancy body mass index (BMI). While there’s no one-size-fits-all number, here are some general guidelines 

• If you were in the healthy weight range before pregnancy, a total gain of 11.5–16 kg over the entire pregnancy is typical.
• By 18 weeks, many people have gained around 4–6 kg, but this can vary.
• If you were underweight, overweight, or obese before pregnancy, your recommended weight gain range will differ, and your doctor or midwife can help tailor advice to your needs.

At 18 weeks pregnant, you might start to feel your baby move—often described as gentle flutters, like butterflies in your tummy. This sensation is called quickening. However, it’s also completely normal not to feel anything yet, especially if this is your first pregnancy. Many people don’t feel distinct movements until around 20–22 weeks.

The 18–20 week ultrasound, also known as the morphology scan, is a detailed check of your baby’s development. It can check the following:

• Checks your baby’s growth and development, including organs, limbs, and spine.

• Examines the placenta’s position, the length of your cervix, and amniotic fluid levels.
• Assesses the umbilical cord and blood flow.
• Can detect conditions like spina bifida, congenital heart disease, and limb differences.
• May prompt further testing if any concerns are found.
• Can often reveal your baby’s sex, if you wish to know (although it’s not always guaranteed).

Yes, dizziness can be normal at 18 weeks pregnant, and it’s often caused by hormonal changes and increased blood flow. During pregnancy, your blood vessels relax and widen, which can lower your blood pressure and lead to light-headedness or dizziness, especially when standing up quickly or getting out of bed.

However, if dizziness is severe, persistent, or accompanied by other symptoms like blurred vision, headaches, or fainting, it’s important to speak with your doctor or midwife, as it could signal something more serious.

Yes, at 18 weeks pregnant, you can usually find out the sex of your baby during the 18–20 week ultrasound scan, also known as the morphology scan.

At 18 weeks pregnant, emotional changes are common and can vary widely. You might feel more vulnerable, tired, or in need of extra support. Some people experience mood swings, anxiety, or low moods, especially if they’ve had mental health challenges in the past. It’s also normal to feel excited, nervous, or even disconnected at times. Hormonal shifts, physical changes, and the reality of becoming a parent can all contribute to these feelings. If you're feeling persistently sad, anxious, or overwhelmed, it's important to talk to your doctor or midwife. Support is available through services like PANDA  (Perinatal Anxiety and Depression Australia) and Beyond Blue , and many hospitals have mental health professionals who can help.

Yes, at 18 weeks pregnant, it is generally safe to sleep on your back, especially if that’s the most comfortable position for you.  Sleeping on your back becomes a concern after 28 weeks, when the growing uterus can press on a major vein (the vena cava) and reduce blood flow to your baby. To prepare for later stages, you might start practicing side sleeping now, especially on your left side, which can improve circulation. Using pillows between your legs or under your bump can help make side sleeping more comfortable.