Spinal muscular atrophy (SMA) is an inheritable disease that involves muscle weakness and atrophy. The underlying cause relates to the progressive degeneration and loss of motor neurons in your spinal cord and brain stem.

While severe forms can result in infantile or adolescent death, if you have type 3 or 4 SMA, you can have a typical life expectancy.

Having SMA during pregnancy may increase your chance of developing complications during pregnancy, including preterm labor and miscarriage.

But pregnancy in people with SMA is not well-studied yet. This means experts do not have a full picture yet of exactly what to expect, but they do have some evidence to suggest that pregnancy with SMA has a higher chance of complications compared with pregnancy without SMA.

Experts do not fully understand yet how SMA affects pregnancy. But here’s what they know so far:

  • There can be an increased chance of preterm labor or cesarean delivery, commonly referred to as a C-section.
  • Complication risks are similar to those of the general population.
  • The pregnant person may need respiratory support.
  • Weakness can often become exasperated.

According to a 2022 case study, if you have SMA, you may have a high risk pregnancy. The authors note possible complications, including:

  • preterm birth
  • miscarriage
  • growth restrictions

A small 2017 study recorded responses from 32 pregnant women with SMA. The participants reported 35 pregnancies, since a few were pregnant with multiples.

The researchers noted both preterm labor and C-section delivery rates were high. They also found that 74% of those in the study reported increased weakness during pregnancy. Also, 42% reported increased weakness following pregnancy.

Despite this, the authors reported that most of the pregnant people with SMA surveyed had a positive experience with good outcomes. Many expressed the desire to have more than one pregnancy.

Experts mention two primary complications if you become pregnant and have SMA: preterm labor and the need to have a C-section.

Doctors consider a baby to be preterm when they are born before 37 weeks. Because a lot of important growth and development occurs in the final weeks of pregnancy, if your child is born early, it can put them at risk of several possible complications, such as:

  • infant death
  • low birth weight
  • vision or hearing difficulties
  • developmental delays
  • cerebral palsy
  • trouble with breathing and feeding

You may need to have a C-section if you are pregnant and have SMA. Though generally safe, it is major surgery with the potential to cause rare complications. These can include:

  • development of blood clots in the legs, pelvic organs, or lungs
  • infection of local tissue and organs
  • moderate to severe loss of blood
  • injury to the bowels or bladder
  • allergic reaction to the anesthetic
  • increased risk of placenta issues or ruptured uterus in future pregnancies

If you have SMA, you may want to discuss the possible complications and plans for your pregnancy. This can help you prepare and be ready for the possible outcomes.

If you have SMA, you may worry about passing it on to your newborn baby. SMA is a recessive trait. This means that to pass it on to your child, your partner would need to be a carrier or have SMA as well. Two parents with SMA gene mutations have a 1-in-4 chance of passing the condition to their child.

If your partner’s results come back negative for the gene, your baby has a lower chance of the condition.

Genetic testing before you become pregnant may help you better prepare for possible outcomes, but it cannot provide 100% certainty about the chances of passing the condition on to your baby. It also cannot tell you how severe SMA will be for your baby if you do pass it on.

Genetic testing typically requires a blood sample. Doctors then send the sample to a lab for analysis.

If you have SMA, you may want to consider talking with a doctor or geneticist before you become pregnant. This may help you in planning your pregnancy and may give your care team a chance to develop a treatment plan based on your needs.

A doctor may recommend getting:

  • genetic testing of your developing baby
  • regular checkups more often during pregnancy
  • bed rest
  • supportive therapy if you have trouble breathing

However, since it is a rare condition, doctors typically do not have a standard of care for it yet. They also may not have heard of it or only know a small amount about it.

According to one interview of a person with SMA who became pregnant, they saw a doctor specializing in high risk pregnancies who did not have an understanding of what SMA was or how it would affect their pregnancy.

This may mean you will need to help educate doctors handling your pregnancy about your condition to help them better understand and provide the best care possible.

Since pregnancy may make symptoms such as weakness worse, you may want to plan for this as much as possible. This may mean asking for extra support from friends or relatives.

If you notice your breathing becomes more labored, contact a doctor as soon as possible for help.

If you are living with SMA, you can still become pregnant. Though experts do not know much yet about outcomes, studies generally report a standard risk of complications. You may experience worsening weakness or trouble breathing.

Your chances of having a preterm birth or a C-section can also be higher. Both of these conditions have some associated risks for either you or your baby.

Doctors may not be familiar with SMA and pregnancy yet. You may need to help educate healthcare professionals about your condition and make plans to get more help when pregnant if possible. Doctors may recommend genetic testing for your partner or baby to help determine the risk of passing SMA on to them.