Maintaining PHE levels during your 2nd trimester of pregnancy

Pregnancy and PKU 2nd trimester booklet

Week 13 through 26 is considered the second trimester of your pregnancy.

View PKU & Pregnancy: What to Expect blog here

View Low Protein Diet Tips To Help You Get Through The 1st Trimester Of Pregnancy blog here

During this time, you will continue to work closely with your clinic as only they can provide the best guidance for you and your baby.

In the 2nd trimester, depending on your pre-pregnancy weight, you will now start gaining about 0.5 – 1 pound per week. During this time period your baby will grow from the size of peach to about the size of an acorn squash.

In the 2nd trimester you may notice the return of your appetite and a desire to eat more. It is still extremely important to keep your phenylalanine (PHE) levels in control, so be sure to continue to work closely with your metabolic dietitian and have a meal plan in place.

If hunger strikes go for your formula first!

You may also benefit from preparing portioned out low-PHE snacks for the week. This may help reduce temptations to grab foods which are not a part of your meal plan when you find yourself hungry and craving a snack.

Here are some pre-portioned low-PHE snack ideas:

  • Make single-serve bags of low protein pretzels, popcorn and cereal
    • Consider gluten-free items*
  • Cut up fresh fruit or fresh pressed fruit snacks
  • Sliced vegetables; such as cucumbers, peppers, zucchini, etc.
  • Portioned out bite-size veggies; such as baby carrots, cherry or grape tomatoes
  • Bake and freeze low protein bread, biscuits, muffins, cookies and more
  • Prepare your favorite low-PHE soup recipes in bulk and freeze in single-serve units – find recipes here


During this trimester you MAY have an increase in your daily PHE tolerance, which means increased food options. Your metabolic dietitian will work closely with you and monitor your blood PHE, but remember PKU formula is still your main source of PKU-friendly protein for both you and your rapidly growing baby.

**Important!** Be sure to read labels and check serving sizes when planning your snacks. PHE content of foods can vary by brand. Remember that not all foods that are gluten-free are low in protein. For more information on finding the PHE content in commons foods, check out  

Request a Nutricia Maternal PKU Starter Kit for more helpful tips and tools to help get you ready for this special time in life.

Maternal PKU Kit
Ask Your Clinic For A Free Kit

Continue reading our PKU and Pregnancy blog series with 3rd Trimester Support for Maternal PKU

All products shown are medical foods are for the dietary management of Phenylketonuria
(PKU) and must be used under medical supervision. Please consult your metabolic healthcare professional prior to making any changes to your PKU diet.

© 2020 – Nutricia North America

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