Last updated Jan. 11, 2018.
Time and again, women are told all the things they can’t do while pregnant. They can’t smoke or drink alcohol. They should be careful about the medications they take and the food they eat. They should work out, but not too hard. It is widely recognized that a mother’s health and genetics impact the risk of pregnancy complications, birth defects, and health problems in a baby. For example, if a pregnant woman has diabetes, she and her baby are at a higher risk for preeclampsia, premature birth, birth defects, difficult labor, and cerebral palsy. But what about the impact of the dad’s genes and overall health?
While the father does not carry the baby in his body, the genes he passes on influence baby’s short- and long-term health. Aside from if baby will get his chocolate-brown eyes or cute dimples, you may be surprised to learn that a dad’s diet and whether or not he smokes, among other factors, also could be doing damage to your future bundle of joy.
The Safe Birth Project supports parents and children with resources on pregnancy, birth, and caring for your little one after she’s welcomed to the world. Below are a few things you should know about how dad’s genes play a role in baby’s life.
Mom and Dad’s Genes: How They Work
Fifty percent of a baby’s genes come from the mother and the other 50% from the father. There are many inherited disorders that arise due to the particular genetic profile of a baby.
Types of Genetic Disorders
- Autosomal recessive: Both parents carry the gene — such as cystic fibrosis, sickle cell anaemia, and thalassaemia. Often, neither parent has any idea they are a carrier.
- Autosomal dominant: Only one parent carries the gene — such as neurofibromatosis, Huntington’s disease and polycystic kidneys (ADPKD). The parent who carries the gene may be affected by the illness, although some present later in life, so they may not be aware at the time of conception.
- X-linked: Inherited only from mother — such as Fragile X syndrome and color blindness.
- Y-linked: Inherited only from father — such as Y chromosome infertility and Swyer syndrome.
- Co-dominant: Inherited from both parents — such as ABO blood group and alpha-1 antitrypsin deficiency. During pregnancy, blood group incompatibility between the mother and the baby can lead to jaundice and increase the risk of cerebral palsy.
- Mitochondrial inheritance: Passed from the mother — such as Leber hereditary optic neuropathy (LHON).
- New mutations: Such as some types of muscular dystrophy, haemophilia and type 1 neurofibromatosis.
- Chromosomal abnormalities: Caused by a missing or extra chromosome — such as Down syndrome, Edwards’ syndrome and Turner syndrome. Research shows that the risk of these disorders increases with both advanced maternal and paternal age.
Diet, Smoking Habits of Both Parents Affect Baby
In the past, doctors believed that expression of genes was set it stone. But in the last 20 years, a new field of research, epigenetics, has uncovered fascinating evidence that the expression and inheritance of genes can be switched on and off by environmental factors.
A recent article from Georgetown University Medical Center reviewed research on the impact of a father’s genes (paternal genomes). They found that environmental factors can alter the expression of genes in the father, the genes he passes on to his children, and the risk of disease in his children. This effect can go on for generations to come.
The researchers at Georgetown discovered these associations:
Father’s (paternal) age
This “has a significant influence on offspring phenotype (expressed characteristics) and the chance of acquiring congenital abnormalities.” Paternal age increased the risk of schizophrenia, autism, and birth defects (heart, gastrointestinal, and muscular defects) and chromosomal abnormalities, including Down syndrome.
When a man has a low calorie intake in pre-adolescence, his children have a decreased risk of cardiovascular disease and diabetes. When he has a high calorie intake, his children have an increased risk. There is also a link between paternal obesity and obesity in a man’s children.
Smoking has been linked to damaged DNA in sperm, which in turn may lead to birth defects.
Fascinating studies in mice show that stress alters gene expression and passes on a reduced reaction to stressors.
The alcohol consumption of the father was found to have “epigenetic effects on sperm DNA, suggesting a role in the development of congenital disorders (like fetal alcohol syndrome) in offspring.” In animal studies, paternal alcohol consumption was linked to low birth weight, heart defects, immune system problems, decreased muscle function, impaired cognitive function and new learning, hyper-responsiveness to stress, and changes to the brain and spleen.
Reassuringly, animal studies also showed that improvements in lifestyle can decrease prevalence of congenital disorders.
Cerebral Palsy and the Link to Genetic Abnormalities
Cerebral palsy is the most common cause of physical disability in children, affecting approximately two in 1,000 live births. A large Norwegian study in 2014 looked at the role of genes in cerebral palsy found that “people born into families in which someone already has cerebral palsy are themselves at elevated risk, depending on their degree of relatedness” (that is, the closer the relation, the higher the risk — the highest being in twins but also going as far as third-degree relatives).
They concluded that the inheritance was multifactorial, involving multiple genes interacting with each other and with environmental factors. Another study found genetic abnormalities in about 9.6% of children with cerebral palsy, but most were due to new mutations (7 out of 10), suggesting that about 3 in 10 have inherited genetic abnormalities (from one, or both parents). Yet another study found that genetics were implicated in 14%.
As genetic research continues, we may gain a clearer picture of the role of parental genes in causing cerebral palsy.
How do I conceive a healthy baby?
While maternal health is vital in prevention of complications of pregnancy, including birth defects, prematurity, and cerebral palsy, the role of the father must not be ignored by any couple wishing to conceive a healthy baby.
If you are a man wishing to conceive, you should:
- Improve your lifestyle. Abstain from smoking, drinking alcohol, and taking illicit drugs. Eat a well-balanced healthy diet rich in fruits and vegetables and maintain a healthy weight. Other lifestyle changes such as stress management, good sleep, and exercise may help, too.
- Find out your genetic profile. Discuss with your doctor if there are any genetic disorders running in your family. They will advise you on the risks and may refer you for preconception counseling.
A detailed rundown of all the ways men can optimize their health before trying to get pregnant is beyond the scope of this article, but we recommend these posts, which give lots of good pointers: