It is an ambient agent which may create a forever deformity and form or function limitation of development or demise of the embryo or prenatal a dose-action. A connection must be signified between the teratogen and the effect and we also need to know the time of exposure the route and the stage of pregnancy exposure.
A slide on fetal development where the Trajan may have affected the development and help you better understand some of these sequelae from the teratogen as you can see the organs develop pretty early on in the embryonic period and the central nervous system continues to develop the entire time.
So, there can always be effects to the central nervous system genitalia are commonly later as well as eyes which can also explain why they are commonly affected as well the first Trajan and while it’s not currently used.
It’s still something that we encounter frequently and testing and should learn about this is diethylstilbestrol it’s an estrogen and it was it’s an agonist of the estrogen receptor after many years.
Deformities of the uterus like a t-shaped uterus the uterine abnormalities can also affect fertility. It does not affect the mother and didn’t affect the infant initially it has long-standing effects the sons of des mothers also have an increased risk for cryptorchidism solid imide is another test favorite and also another medication that is no longer used.
It was a chemical that was applied in the sixties for nausea especially nausea kinetosis. The effects from the lid imide included limb reduction defects facial hemangiomas duodenal imperforation and heart flaws, kidney infertility, and urinary zone anomalies.
General defects and abnormalities of teeth were also seen the defects directly correlated to development at the gestational age of exposure just like when you look at that chart we have earlier thalidomide is believed to interfere with the neural crest based glaucoma organization.
Exposure to Teratogens:
During development, the sclera terms make up the musculature, so it affects how they develop and how they spread from the neural crest. It’s the lid amide is also an inhibitor of angiogenesis and directly correlates and directly correlates with its teratogenicity.
This picture here is just an example of one of the limb defects you can see with solidified phenylketonuria or otherwise known as PKU is also another test favorite PKU and presents in women who lack the enzyme to break down phenylalanine and can have high levels in their blood.
Especially after ingesting artificial sugar otherwise known as aspartame so phenylalanine can build up in the brain and decrease levels of other amino acids that are necessary for protein and neurotransmitter synthesis.
It can also cause demyelination maternal PKU can lead to within the womb and postpartum development retardation, heart flaws, and garbled thighs phenylalanine can cross the placenta and can build up in the fetus as well a quarter of pregnancies in mothers with PKU will spontaneously abort when the level of phenylalanine.
The mother is greater than 20 milligrams per millilitre there’s a high likelihood of intellectual disability microscopically and intrauterine growth retardation and fetus PKU is part of the newborn screen.
Which is every newborn that’s born in the country has a panel of tests that are done right away and PKU is something that’s tested for PKU is recessive mother’s PKU mothers tend to have heterogeneous children.
So, they might be Fino typically normal in regards to PKU but they might have the birth defects that we just discussed earlier lithium is a commonly used medication for the treatment of bipolar disorder with women who are on lithium who are desiring pregnancy.
Misoprostol so misoprostol is a synthetic prostaglandin e1 analog commonly it has been used for gastric and duodenal ulcers and it also is currently used for a labor induction under the name.
Cytotec misoprostol can be used for medical abortion in combination with my favorite stone like we discussed earlier.
It works by causing a transient drop in the circulation of the fetus via uterine hyperstimulation some studies showed malformations in rats and rabbits and two fetuses severe malformations have been reported in countries where misoprostol is used for abortion alone or without medical supervision.
It is not very effective in medical abortion alone it mostly just causes increased contraction and labor induction the malformations that have been seen in humans include cranial nerve defects especially pairs six and seven this is something called Moebius syndrome.
There was one reported case event in France under medical supervision so that is something that could occur and then various limit or maladies can also occur but are also very rare the cranial nerve defects in Moebius syndrome are rarely detectable by sonography so there’s not much monitoring you can do when there’s continued pregnancy after using misoprostol the next medication is methotrexate.
Methotrexate also kind of in the line of medical abortion it’s formerly known as um Amitha Turin it’s a chemotherapy agent and immunosuppressant so it’s currently used very frequently for autoimmune disorders also for medical abortions especially ectopic pregnancies so methotrexate works as an anti-Foley it competitively inhibits dihydrofolate reductases.
Which helps create tetrahydrofolate so tetrahydrofolate or folic acid is necessary for purine and pyrimidine biosynthesis so in a developing fetus folic acid is extremely necessary and this is also how methotrexate worked as a chemotherapy agent.
It can also as a medication used in abortion methotrexate can cause hepatic toxicity ulcerative stomatitis leukopenia in and is also teratogenic as a teratogen it can cause a multitude of defects including growth deficiency microcephaly hypoplasia of the skull and bones a wide nose link.
Smaller appendages and syndactyly pulmonary atresia and tetralogy of flow which are cardiovascular congenital cardiovascular conditions can also occur exposure between six to eight weeks after conception with levels of 10 milligrams per week or greater are most associated with methotrexate embryo a–they so this brings us to folic acid deficiency.
As a teratogen in and of itself so folic acid deficiency or antagonism can cause neural tube defects such as spinal bifida and anencephaly which means a lack of brain peri conception intake reduces the risk.
So we always recommend women that are trying to conceive to start taking folic acid and build up their levels folic acid deficiency can also cause anemia.
The mother and you also would like to test for b12 deficiency as they can often mask each other preview with a previous pregnancy resulting in a neural tube defect does have an increased risk of subsequent affected pregnancy this image right here just shows.
We’ll move on to lead is commonly tested on the boards and also later on during pediatrics rotations so led produces sensitive O2 molecules and hinders the production of antioxidants so females having earlier lead toxin can donate to her baby since bones stores it and may discharge after a long time. Lead poisoning is considered a blood lead level of greater than 50 micrograms per deciliter but most of the negative effects can be seen at greater than 20. Lead can cross the placenta at:
- Twelve to fourteen weeks of pregnancy·
- Stores in the prenatal·
- May result in abrupt miscarriage ·
The death of a baby can also increase the risk of hemangiomas lymph and angiomas hydrocele.
There is also a factual Association so factor L is a group of symptoms and anomalies that tend to go together and you’ll see that a few of the teratogen’s in this list are also associated with the bacterial so vertebral anomalies and erectile malformations cardiac anomalies trachea esophageal fistula X omphalos and so that’s usually like a mid line abdominal defect renal anomalies and limb Nam Elise.
An example of a limb anomaly from lead poisoning next we’ll move on to obesity and diabetes they’re not necessarily considered teratogen but they do have teratogenic effects and come into play all the time so definitely should be discussed maternal obesity is associated with macrosomia which is a big baby hypertension preeclampsia which is hypertension during pregnancy that can also have associated symptoms gestational diabetes mellitus which is the diabetes of pregnancy and even fetal.
Death uncontrolled diabetes can lead to persistent hyperglycemia and the mother and also periods of hypoglycemia so hyperglycemia inhibits myo-inositol uptake. Which is crucial for the growth of the embryo in pregnancy and neural Asian phases of embryo development can also cause anomalies in their arachidonic acid prostaglandin route. This leads to growth retardation and neural tube defects so that hemoglobin a1c can provide a marker as well so hemoglobin greater than a hemoglobin a1c greater than 11.5 is associated.
- So, there is a 25% risk of fetal abnormality when using oral Accutane Retin-A or retinoic acid Increased risk of transposition of the great vessels coming off the heart in the fetus
- A ventricular septal defect dextrocardia anencephaly spina bifida· Hydrocephalus ·
- Again, there is a vector association with high blood sugars that is a fetus or the newborn that is born can also have respiratory distress syndrome hyperbilirubinemia hypocalcemia, and vascular thrombosis.·
- The next teratogen is hypothyroidism
Hypothyroidism in the fetus is or in the newborn is usually when the fetal gland is suppressed by antithyroid medication that the mother is taking so PT you carbons all iodides or maternal antibodies to the thyroid gland, while gestation period, augmented obligation for love with our oxen just based on how much of the hormone is available.
How hormone-binding globulin is affected during pregnancy so generally the requirements tend to go up by 25 to 50 percent during pregnancy there is an increased risk of:
- Anemia placental abruption preeclampsia
- Postpartum hemorrhage and a mother with hypothyroidism congenital hypothyroidism were formerly known as cretinism
- Developmental abnormalities if not treated right away hypothyroidism is another that is commonly screened for in the newborn just like PKU.