2nd Trimester Nutrition: Managing Constipation & Healthy Weight Gain

The second trimester is often described as the “honeymoon phase” of pregnancy. 

For many women, nausea and food aversions begin to ease, energy levels improve, and the growing baby bump becomes more noticeable!

But along with these positive changes, there are some things to be mindful of: constipation and healthy weight gain.

Why Constipation Happens in the Second Trimester

Constipation affects up to 38% of pregnant women, particularly in the second and third trimesters (Cullen et al., 2007). It’s not just uncomfortable — it can impact your appetite, energy, and overall well being.

The main culprits?

• Hormonal changes: Increased progesterone slows gut movement.

• Pressure from the growing uterus on the intestines.

• Iron supplements, which are often prescribed during pregnancy, can make stools harder and more difficult to pass.

• Reduced fluid intake 

• Less physical activity

How to Relieve Constipation Naturally

1. Fibre first

Aim for 25–30g of fibre per day from whole foods. Some pregnancy-friendly, high-fibre options:

• Rolled oats, wholemeal toast, brown rice

• Fruits like pears, kiwi, and berries

• Vegetables such as sweet potato, carrots, and broccoli

• Legumes like chickpeas and lentils (as tolerated)

• Chia seeds and ground flaxseeds

• Hydration matters

Fibre works best with plenty of fluids. Try to sip on at least 2–2.5L of water daily. If water feels boring, infuse it with fruit or try a warm cup of water with lemon in the morning to gently stimulate digestion.

2. Gentle movement helps

Even light activities like walking or prenatal yoga can help get things moving in your digestive tract.

3. Check your iron supplement

If your iron tablet is worsening constipation, speak to your doctor or midwife. Some forms (like ferrous bisglycinate) may be gentler on your gut (Milman, 2006).

Understanding Healthy Weight Gain in the Second Trimester

Now that your body is supporting your baby’s rapid growth, healthy weight gain becomes more noticeable — and important.

But how much is “normal”? According to the Institute of Medicine (IOM), healthy weight gain depends on your pre-pregnancy BMI:

Pre-pregnancy BMI	Recommended Total Gain	Weekly Gain (2nd & 3rd trimester)
Underweight (<18.5)	12.5–18 kg	~0.5 kg/week
Normal (18.5–24.9)	11.5–16 kg	~0.4–0.5 kg/week
Overweight (25–29.9)	7–11.5 kg	~0.3 kg/week
Obese (≥30)	5–9 kg	~0.2 kg/week

Keep in mind — these are averages. Everyone’s journey is different, and your needs may vary depending on your health, activity level, and appetite.

Foods That Support Healthy Weight Gain

Instead of thinking about “eating for two,” try to focus on eating well for you and your baby. The quality of your food matters more than the quantity.

Some nourishing snack and meal ideas include:

• Smoothie with banana, yoghurt, oats, and nut butter

• Avocado on whole grain toast with a poached egg

• Stir-fried vegetables with brown rice and tofu

• Trail mix or a handful of almonds and dried fruit

• Full-fat Greek yoghurt with berries and a sprinkle of chia seeds

If your appetite is growing, that’s perfectly normal. Just aim to honour your hunger with nourishing options most of the time — and enjoy your favourite treats too. Balance is key.

In Conclusion

The second trimester can be a wonderful opportunity to refocus on your health and nutrition. Whether you’re trying to relieve constipation or ensure you’re gaining weight in a healthy way, small daily choices can make a big difference.

Be kind to your body. Nourish it with whole foods, move in ways that feel good, and listen to your hunger cues. If you’re struggling with ongoing constipation or are unsure about your weight gain, it’s always worth checking in with your doctor or a dietitian for personalised support.

You’re doing an amazing job, and every meal is a chance to support both you and your growing baby!

References:

• Cullen, G., O’Donoghue, D., & Keeling, P. W. (2007). Constipation and pregnancy. Best Practice & Research Clinical Gastroenterology, 21(5), 807–818.

• National Health and Medical Research Council (NHMRC). (2006). Nutrient Reference Values for Australia and New Zealand.

• Milman, N. (2006). Iron prophylaxis in pregnancy—general or individual and in which dose? Annals of Hematology, 85(12), 821–828.

• Institute of Medicine (IOM). (2009). Weight Gain During Pregnancy: Reexamining the Guidelines.