18 Weeks Pregnant: Should You Get Vaccinated?

• Your Baby at 18 Weeks

Your baby is beginning to settle into a sleep and wake cycle—though no alarm clock needed! They may even have a favourite snoozing spot…like right on top of your bladder. When awake, their kicks and wriggles are getting stronger, so those once-delicate flutters might now feel like proper thumps.

Even though your baby’s eyelids are still fused shut, their little eyes are making blink-like movements. Meanwhile, their nervous system continues to develop as their nerves become wrapped in a protective fatty layer called myelin—think of it as insulation around copper wiring. They’re also developing fat stores, including an essential type called brown fat, which acts like an internal candle to help keep them warm once they’re born.

All babies, regardless of sex, start out with the same basic structures. By now, girls will have a uterus and fallopian tubes in place, while boys’ penises are developed, though the testes haven’t yet dropped into the scrotum (sometimes this can take months—or even years—after birth).

How Many Months is 18 Weeks Pregnant?

Eighteen weeks pregnant is just over four months along.

Baby’s Size at 18 Weeks

At 18 weeks, your baby is about the size of a sweet potato.

18 Weeks Pregnant: What to Expect

Welcome to the sweet spot of the second trimester! Many expectant parents notice they’re finally regaining energy, enjoying more balanced meals again (veggies and protein, welcome back!), and feeling more inclined to exercise.

It’s also time to start thinking about vaccinations. Both the flu jab and the whooping cough (pertussis) vaccine are recommended during pregnancy and considered safe.

• Flu jab: Pregnant people are more vulnerable to complications from influenza, and flu can also be dangerous for babies. If your pregnancy overlaps with flu season, your GP or midwife will advise you to get immunised as early as possible.
• Whooping cough (pertussis/Tdap): Usually given in the third trimester, this vaccine protects your baby through you until they’re old enough for their own jabs at 2 months. Research shows that babies whose mums had the jab during pregnancy were well protected in those early, vulnerable weeks.

18 Weeks Pregnant To-Do List

• Discuss your worries with your care provider: Whether you’re anxious about weight gain, birth defects, or labour pain, you’re not alone—every expectant parent has concerns. Write down your questions and bring them to your next appointment. Talking them through often makes them feel far less daunting.
• Begin your birth plan: Chat with your partner about your hopes for labour and delivery, from pain relief options (hypnobirthing, epidural, water birth) to preferences like having a doula, delayed cord clamping, or immediate skin-to-skin. Draft your plan and review it with your midwife or doctor—but remember, flexibility is key! Birth can be unpredictable, and that’s completely normal.
• Protect your family: Now’s the time to think about some grown-up essentials: updating insurance, checking smoke alarms, drafting a will, and even naming a guardian for your child—just in case. Having these steps in place offers peace of mind.

Pregnancy Quote of the Week

"The moment a child is born, the mother is also born. She never existed before. The woman existed, but the mother, never. A mother is something absolutely new." —Rajneesh

Disclaimer: The information on our site is NOT medical advice for any specific person or condition. It is only meant as general information. If you have any medical questions and concerns about your child or yourself, please contact your health provider. Breastmilk is the best source of nutrition for babies. It is important that, in preparation for and during breastfeeding, mothers eat a healthy, balanced diet. Combined breast- and bottle-feeding in the first weeks of life may reduce the supply of a mother's breastmilk and reversing the decision not to breastfeed is difficult. If you do decide to use infant formula, you should follow instructions carefully.