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Planning for pregnancy and a healthy baby

couple. to convey idea of creating a family

Having Phenylketonuria (PKU) yourself doesn’t necessarily mean the disorder will be passed on to your baby. However, your unborn child is nonetheless at risk of complications. High levels of Phenylalanine (Phe) in your blood will expose the developing foetus to the serious likelihood of brain damage. Other problems like intrauterine growth retardation, congenital heart defects and facial deformity are also possible.

Before falling pregnant, take time to visit your PKU specialist to ensure that you’re doing everything you can to lower your blood Phe levels. Ideally, you should reach and maintain a blood Phe level of 2 mg/dl (120 µmol/l) during the six months preceding conception.

Women with PKU who maintain good control of their blood Phenylalanine (Phe) levels before and during pregnancy stand an excellent chance of a normal neonatal outcome8. It’s likely your blood Phe levels will be measured twice a week. However achieving safe levels requires major commitment and support. Your PKU specialist will be able to advise on treatment options to help maintain optimum blood Phe levels.

Research suggests that women with PKU often relax Phe control during later pregnancies in comparison to their first. But controlling blood Phe levels is important to every baby.

See The genetics of PKU

Asking the right questions about PKU

Pregnancy is a big undertaking in any woman’s life. If you have PKU, it carries additional risks, not only to yourself, but your unborn child. The ideal time to see your PKU specialist is long before conception so you can prepare and maximise your chances of a safe pregnancy.

Your PKU specialist will provide target blood Phenylalanine (Phe) levels for the six months preceding conception and provide advice on how to reach them. You may like to download this list of questions to add to your own.

Screening for PKU

Screening for Phenylketonuria (PKU) is possible, but the results are not always precise. This is because there are more than 500 mutations of the liver enzyme PAH which lead to high levels of Phe in the blood.

Prevention is only possible when a couple already has a baby with PKU. Two options then exist: pre embryo selection using in vitro fertilisation or prenatal amniocentesis or chorionic villus sampling. DNA samples are taken from both parents for comparison.

Information for women seeking to become pregnant

Learn about the importance of maintaining low blood Phe levels before and during pregnancy.

Find easy ways to manage PKU and keep your Phe levels low.

Find out how to keep you baby with PKU healthy.

Eczema

A skin condition which causes the skin to appear red, swollen and itchy.

Enzyme

A kind of biological molecule that facilitates certain chemical reactions inside the body. People with Phenylketonuria (PKU) lack a certain enzyme called Phenylalanine Hydroxylase (PAH).

Amino acid

A type of molecule found inside protein. There are 20 amino acids that are considered standard. Of those, 10 are essential to a healthy diet because the body is unable to produce them. Among the 10 essential amino acids is Phenylalanine.

Amniocentesis

A prenatal test in which cells are collected from the amniotic sac in order to detect chromosomal abnormalities.

Amniotic sac

The thin-walled bag that contains the protective liquid that surrounds the foetus during its development in the womb.

PAH (Phenylalanine Hydroxylase)

An enzyme which works together with Tetrahydrobiopterin (BH4) to convert Phenylalanine (Phe) to Tyrosine (Tyr) in the liver. A deficiency in PAH results in high Phenylalanine levels in the blood, which is the biochemical hallmark of Phenylketonuria (PKU).

Phenotype

An observable characteristic or trait of an organism. Phenotypes result from the expression of an organism’s genes as well as the influence of environmental factors.

phenylalanine (Phe) tolerance

The quantity of Phe a patient may consume without a significant increase in her or his target blood Phe levels. Usually expressed as daily intake.

Phenylalanine (Phe)

A building block of protein, and one of the 10 essential amino acids. An inability to metabolize excess phenylalanine is the characteristic feature of Phenylketonuria (PKU). When the blood concentration of Phenylalanine exceeds what is considered a healthy level, excess amounts may build up in the brain, causing mental retardation.

Phenylalanine Hydroxylase

See PAH.

Phenylketonuria

See PKU.

PKU (Phenylketonuria)

An inherited metabolic defect in protein metabolism. In PKU, the Phenylalanine Hydroxylase (PAH) enzyme is unable to convert Phenylalanine to Tyrosine, resulting in a build-up of Phenylalanine (Phe) in the blood that eventually passes into the brain, causing mental retardation and other neurological problems.

Protein

A type of molecule produced by the body from Amino acids.