You are unique and your diet will be tailored for your pregnancy by your metabolic dietitian. Your diet is likely to change several times throughout your pregnancy to keep your phe levels in range.
This will be linked to many factors including your weight before becoming pregnant, your phe tolerance, how far into your pregnancy you are, the growth of your baby and what you like to eat and drink.
Whether you were expecting to become pregnant or it was a surprise, it is important to let your metabolic team know as soon as you have a positive pregnancy test as you must follow a strict pre-conception diet. This is so they can give you the right advice for you and your baby. It is also important to make early contact with your GP/Midwife to ensure a referral to the appropriate obstetric/gynaecology service is made.
Maintaining blood phe levels in the target range in the early weeks of pregnancy is important to protect your baby’s heart and brain as they start to form.
Dietary phe tolerance is lowest in the first trimester so your diet will likely be very restrictive. As your phe tolerance is so low, you might find small changes in your eating patterns can affect your phe level. Try to keep your dietary intake, including protein substitutes, as regular and stable as possible.
Pregnancy associated nausea and vomiting, viruses, infections and changes in appetite can make consuming enough calories or protein substitute very difficult. This can lead to high phe levels. Tips on how this can be best handled can be found below.
After approximately 16 weeks of pregnancy your phe exchanges can increase rapidly as the baby grows. Your dietitian will advise you on how to increase your dietary phe. Having low phe levels (below 100µmol/L) during pregnancy has been linked to slower growth in babies. So, it is important to follow the advice of your dietitian.
For ideas of recipes with adaptable phe exchanges, download recipe booklet here.
Getting the right nutrition throughout pregnancy is important for you and your baby. Your protein substitute (and the extra vitamins and minerals) are vital for helping to keep your phe low and providing the right nutrients for growth. Nutrients like protein, iron, iodine, vitamin B₁₂, essential fatty acids (DHA) and folic acid are important for the baby’s growth and the development of their heart and brain. It’s important to follow the recommendations from your dietitian to get the right nutrients.
Nausea (feeling sick) and vomiting during pregnancy is normal whether you have PKU or not. It is often worse on waking in the morning but can happen at any time of day. Not all women will get morning sickness, but it is very common in early pregnancy and usually clears up by 16-20 weeks of pregnancy.
In PKU, pregnancy associated nausea and vomiting can affect your appetite and ability to take your protein substitute. If you are not managing to take your protein substitute or enough energy (calories) your phe levels will increase.
If you are feeling sick or struggling to take your protein substitute it is important to tell your metabolic team as soon as possible. Nausea and vomiting can often be managed more proactively in pregnancy and PKU. Anti-sickness medications called anti-emetics may be recommended to control the nausea and vomiting to help limit any rise in phe levels. Sometimes an admission to hospital is required to assess the condition and determine the best course of management for you and your baby and rule out any other cause for the nausea and vomiting. For example, urinary infections.
Here are some tips for dealing with nausea or sickness in a PKU pregnancy which can be followed in discussion with your dietitian:
Managing to balance energy (calorie) intake in pregnancy is tricky, and even more so in PKU.
Your Metabolic Dietician Will:
Your weight and the baby’s growth will be checked at your appointments with your midwife or obstetric team.
If you’re feeling sick or have a poor appetite it can be difficult to get enough energy (calories). Some tips to get extra energy in a low protein diet are:
Your dietitian will be able to provide tailored advice for you if you need to limit your energy intake in pregnancy. Some tips to limit extra energy for a low protein diet are:
Download the recipe booklet for tasty recipes which can be adapted to your exchanges and energy needs here.
Pregnancy is an exciting time, with a lot to consider especially when you have PKU, planning and being organised can help you as your pregnancy progresses.