Babies with chromosomal conditions have a problem in one or more of their chromosomes. Chromosomes are the structures that hold genes. Genes are part of your body's cells that store instructions for the way your body grows and works. Genes are passed from parents to children.
Each person has 23 pairs of chromosomes, or 46 in all. For each pair, you get one chromosome from your mother and one chromosome from your father.
About 1 in 150 babies is born with a chromosomal condition. Down syndrome is an example of a chromosomal condition. Because chromosomes and genes are so closely related, chromosomal conditions are also called genetic conditions.
What causes chromosomal conditions?
Chromosomal conditions are caused by two kinds of changes in chromosomes:
- Changes in the number of chromosomes—This means you have too many or too few chromosomes.
- Changes in the structure of chromosomes—This means that part of a chromosome may be missing, repeated or rearranged.
Both kinds of changes can be inherited. This means they’re passed from parent to child. Or they can happen randomly as cells develop.
What problems can chromosomal conditions cause?
Sometimes chromosomal conditions can cause miscarriage. This is when a baby dies in the womb before 20 weeks of pregnancy. More than half of miscarriages are caused by chromosomal conditions. These conditions also can cause stillbirth, which is when a baby dies in the womb before birth but after 20 weeks of pregnancy.
Each child born with a chromosomal condition is different. Some children with chromosomal conditions have intellectual disabilities or birth defects, or both. Some children with these conditions don’t have any serious problems. The problems depend on which chromosomes are affected and how.
How do you know if your baby has a chromosomal condition?
The American College of Obstetricians and Gynecologists (ACOG) recommends that all pregnant women be offered prenatal tests for Down syndrome and other chromosomal conditions. A screening test is a medical test to see if you or your baby is more likely than others to have a certain health condition.
You can have screening tests in the first or second trimester of pregnancy. First trimester screening is done at 11 to 13 weeks of pregnancy. Along with a blood test, you get a special ultrasound that checks the back of your baby’s neck. Testing in the second trimester is called maternal blood screening. You can get this blood test between 15 and 20 weeks of pregnancy.
If a screening test shows that your baby may have a problem, your provider gives you a diagnostic test. This is a medical test to see if you do or don't have a certain health condition. Diagnostic tests include amniocentesis or chorionic villus sampling. Your provider also can check your baby’s blood for chromosomal conditions after he’s born.
What are the chances of your baby having a chromosomal condition?
As you get older, there’s a greater chance of having a baby with certain chromosomal conditions, like Down syndrome. For example, at age 35, your chances of having a baby with a chromosomal condition are 1 in 192. At age 40, your chances are 1 in 66.
If you or someone in your family has a chromosomal condition, or if you have a baby with a chromosomal condition, talk to a genetic counselor. A genetic counselor is a person who is trained to know about genetics, birth defects and other medical problems that run in families. She can help you understand the causes of chromosomal conditions, what kind of testing is available, and your chances of having a baby with these conditions. If you already have a baby with a chromosomal condition, the chances of having another baby with the same condition are usually low.
For more information
Chromosome Disorder Outreach
National Down Syndrome Society
National Organization for Rare Disorders
Last reviewed February 2013
See also: Birth defects, Genetic counseling,Your family health history
Frequently Asked Questions
Can dad's exposure to chemicals harm his future kids?
Dad's exposure to harmful chemicals and substances before conception or during his partner's pregnancy can affect his children. Harmful exposures can include drugs (prescription, over-the-counter and illegal drugs), alcohol, cigarettes, cigarette smoke, chemotherapy and radiation. They also include exposure to lead, mercury and pesticides.
Unlike mom's exposures, dad's exposures do not appear to cause birth defects. They can, however, damage a man's sperm quality, causing fertility problems and miscarriage. Some exposures may cause genetic changes in sperm that may increase the risk of childhood cancer. Cancer treatments, like chemotherapy and radiation, can seriously alter sperm, at least for a few months post treatment. Some men choose to bank their sperm to preserve its integrity before they receive treatment. If you have a question about a specific exposure, contact the Organization of Teratology Information Specialists at www.otispregnancy.org.
Can Rh factor affect my baby?
The Rh factor may be a problem if mom is Rh-negative but dad is Rh-positive. If dad is Rh-negative, there is no risk.
If your baby gets her Rh-positive factor from dad, your body may believe that your baby's red blood cells are foreign elements attacking you. Your body may make antibodies to fight them. This is called sensitization.
If you're Rh-negative, you can get shots of Rh immune globulin (RhIg) to stop your body from attacking your baby. It's best to get these shots at 28 weeks of pregnancy and again within 72 hours of giving birth if a blood test shows that your baby is Rh-positive. You won't need anymore shots after giving birth if your baby is Rh-negative. You should also get a shot after certain pregnancy exams like an amniocentesis, a chorionic villus sampling or an external cephalic version (when your provider tries to turn a breech-position baby head down before labor). You'll also want to get the shot if you have a miscarriage, an ectopic pregnancy or suffer abdominal trauma.
Does cleft lip or cleft palate cause dental problems?
A cleft lip or cleft palate that extends into the upper gums (where top teeth develop) can cause your baby to have certain dental problems, including:
- Missing teeth
- Too many teeth
- Oddly shaped teeth
- Teeth that are out of position around the cleft
Every baby with a cleft lip or palate should get regular dental checkups by a dentist with experience taking care of children with oral clefts. Dental problems caused by cleft lip or palate usually can be fixed. If needed, your baby can get ongoing care by a team of experts, including:
- A dentist
- An orthodontist to move teeth using braces
- An oral surgeon to reposition parts of the upper jaw, if needed, and to fix the cleft
See also: Cleft lip and cleft palate
Does cleft lip or cleft palate cause ear problems?
Cleft lip does not cause ear problems.
Babies with cleft palate, however, are more likely than other babies to have ear infections and, in some cases, hearing loss. This is because cleft palate can cause fluid to build up in your baby’s middle ear. The fluid can become infected and cause fever and earache. If fluid keeps building up with or without infection, it can cause mild to moderate hearing loss.
Without treatment , hearing loss can affect your baby’s language development and may become permanent.
With the right care, this kind of hearing loss is usually temporary. Your baby’s provider may recommend:
- Having your baby’s ears checked regularly for fluid buildup
- Medicines for treating fluid buildup and ear infections
- Ear tubes if your baby has fluid in his ears over and over again. Ear tubes are tiny tubes that are inserted into the eardrum to drain the fluid and help prevent infections.
See also: Cleft lip and cleft palate
Does cleft lip or cleft palate cause problems with breastfeeding?
Babies with only a cleft lip usually don’t have trouble breastfeeding. Most of the time, they can breastfeed just fine. But they may need some extra time to get started.
Babies with cleft lip and palate or with isolated cleft palate can have:
- Trouble sucking strong enough to draw milk through a nipple
- Problems with gagging or choking
- Problems with milk coming through the nose while feeding
Most babies with cleft palate can’t feed from the breast. If your baby has cleft palate, he can still get the health benefits of breastfeeding if you feed him breast milk from a bottle. Your provider can show you how to express (pump) milk from your breasts and store breast milk.
Your baby’s provider can help you start good breastfeeding habits right after your baby is born. She may recommend:
- Special nipples and bottles that can make feeding breast milk from a bottle easier
- An obturator. This is a small plastic plate that fits into the roof of your baby’s mouth and covers the cleft opening during feeding.
See also: Cleft lip and cleft palate, Breastfeeding
Does cleft lip or cleft palate cause speech problems?
Children with cleft lip generally have normal speech. Children with cleft lip and palate or isolated cleft palate may:
- Develop speech more slowly
- Have a nasal sound when speaking
- Have trouble making certain sounds
Most children can develop normal speech after having cleft palate repair. However, some children may need speech therapy to help develop normal speech.
See also: Cleft lip and cleft palate
What are choroid plexus cysts?
The choroid plexus is the area of the brain that produces the fluid that surrounds the brain and spinal cord. This is not an area of the brain that involves learning or thinking. Occasionally, one or more cysts can form in the choroid plexus. These cysts are made of blood vessels and tissue. They do not cause intellectual disabilities or learning problems. Using ultrasound, a health care provider can see these cysts in about 1 in 120 pregnancies at 15 to 20 weeks gestation. Most disappear during pregnancy or within several months after birth and are no risk to the baby. They aren't a problem by themselves. But if screening tests show other signs of risk, they may indicate a possible genetic defect. In this case, testing with higher-level ultrasound and/or amniocentesis may be recommended to confirm or rule out serious problems.
What if I didn't take folic acid before pregnancy?
If you didn’t take folic acid before getting pregnant, it doesn't necessarily mean that your baby will be born with birth defects. If women of childbearing age take 400 micrograms of folic acid every day before and during early pregnancy, it may help reduce their baby’s risk for birth defects of the brain and spin called neural tube defects (NTDs). But it only works if you take it before getting pregnant and during the first few weeks of pregnancy, often before you may even know you’re pregnant.
Because nearly half of all pregnancies in the United States are unplanned, it's important that all women of childbearing age (even if they're not trying to get pregnant) get at least 400 micrograms of folic acid every day. Take a multivitamin with folic acid before pregnancy. During pregnancy, switch to a prenatal vitamin, which should have 600 micrograms of folic acid.
Last reviewed November 2012