About one third of children whose mothers are taking this drug during pregnancy typically have intrauterine growth restriction with a small head and develop minor dysmorphic craniofacial features and limb defects including hypoplastic nails and distal phalanges (birth defects). A smaller population will have growth problems and developmental delay, or intellectual disability. Methemoglobinemia is a rarely seen side effect.

Heart defects and cleft lip may also be featured.

Fetal trimethadione syndrome is characterized by the following major symptoms as a result of the teratogenic characteristics of trimethadione.

- Cranial and facial abnormalities which include; microcephaly, midfacial flattening, V-shaped eyebrows and a short nose

- Cardiovascular abnormalities

- Absent kidney and ureter

- Meningocele, a birth defect of the spine

- Omphalocele, a birth defect where portions of the abdominal contents project into the umbilical cord

- A in mental and physical development

Neu-Laxova syndrome presents with severe malformations leading to prenatal or neonatal death. Typically, NLS involves characteristic facial features, decreased fetal movements and skin abnormalities.

Fetuses or newborns with Neu–Laxova syndrome have typical facial characteristics which include proptosis (bulging eyes) with eyelid malformations, nose malformations, round and gaping mouth, micrognathia (small jaw) and low set or malformed ears. Additional facial malformations may be present, such as cleft lip or cleft palate. Limb malformations are common and involve the fingers (syndactyly), hands or feet. Additionally, edema and flexion deformities are often present. Other features of NLS are severe intrauterine growth restriction, skin abnormalities (ichthyosis and hyperkeratosis) and decreased movement.

Malformations in the central nervous system are frequent and may include microcephaly, lissencephaly or microgyria, hypoplasia of the cerebellum and agenesis of the corpus callosum. Other malformations may also be present, such as neural tube defects.

Fetal hydantoin syndrome, also called fetal dilantin syndrome is a group of defects caused to the developing fetus by exposure to teratogenic effects of phenytoin or carbamazepine. Dilantin is the brand name of the drug phenytoin sodium in the United States, commonly used in the treatment of epilepsy.

It may also be called congenital hydantoin syndrome, Fetal Hydantoin Syndrome, Dilantin Embryopathy, or Phenytoin Embryopathy.

Association with EPHX1 has been suggested.

Fetal trimethadione syndrome (also known as paramethadione syndrome, German syndrome, tridione syndrome, among others) is a set of birth defects caused by the administration of the anticonvulsants trimethadione (also known as Tridione) or paramethadione to epileptic mothers during pregnancy.

Fetal trimethadione syndrome is classified as a rare disease by the National Institute of Health's Office of Rare Diseases, meaning it affects less than 200,000 individuals in the United States.

The fetal loss rate while using trimethadione has been reported to be as high as 87%.

Hydrolethalus syndrome can cause heart and brain defects, a cleft lip or palate, an abnormally shaped nose or jaw, or incomplete lung development. These defects are typically serious enough to cause stillbirth or death within a few days of birth.

Hydrolethalus can be readily diagnosed during pregnancy through the use of ultrasound, which will often reveal hydrocephaly and an abnormal structure of the brain.

Neu–Laxova syndrome (also known as Neu syndrome or Neu-Povysilová syndrome, abbreviated as NLS) is a rare autosomal recessive disorder characterized by severe intrauterine growth restriction and multiple congenital malformations. Neu–Laxova syndrome is a very severe disorder, leading to stillbirth or neonatal death. It was first described by Dr. Richard Neu in 1971 and Dr. Renata Laxova in 1972 as a lethal disorder in siblings with multiple malformations. Neu–Laxova syndrome is an extremely rare disorder with less than 100 cases reported in medical literature.

Several terms are used to describe congenital abnormalities. (Some of these are also used to describe noncongenital conditions, and more than one term may apply in an individual condition.)

It can be detected by the naked eye as well as dental or skull X-Ray testing.

Much of the language used for describing congenital conditions predates genomic mapping, and structural conditions are often considered separately from other congenital conditions. It is now known that many metabolic conditions may have subtle structural expression, and structural conditions often have genetic links. Still, congenital conditions are often classified in a structural basis, organized when possible by primary organ system affected.

Of those fetuses that do survive to gestation and subsequent birth, common abnormalities may include:

- Nervous system

- Intellectual disability and motor disorder

- Microcephaly

- Holoprosencephaly (failure of the forebrain to divide properly).

- Structural eye defects, including microphthalmia, Peters' anomaly, cataract, iris or fundus (coloboma), retinal dysplasia or retinal detachment, sensory nystagmus, cortical visual loss, and optic nerve hypoplasia

- Meningomyelocele (a spinal defect)

- Musculoskeletal and cutaneous

- Polydactyly (extra digits)

- Cyclopia

- Proboscis

- Congenital trigger digits

- Low-set ears

- Prominent heel

- Deformed feet known as rocker-bottom feet

- Omphalocele (abdominal defect)

- Abnormal palm pattern

- Overlapping of fingers over thumb

- Cutis aplasia (missing portion of the skin/hair)

- Cleft palate

- Urogenital

- Abnormal genitalia

- Kidney defects

- Other

- Heart defects (ventricular septal defect) (Patent Ductus Arteriosus)

- Dextrocardia

- Single umbilical artery

Patients diagnosed with porencephaly display a variety of symptoms, from mild to severe effects on the patient. Patients with severe cases of porencephaly suffer epileptic seizures and developmental delays, whereas patients with a mild case of porencephaly display little to no seizures and healthy neurodevelopment. Infants with extensive defects show symptoms of the disorder shortly after birth, and the diagnosis is usually made before the age of 1.

The following text lists out common signs and symptoms of porencephaly in affected individuals along with a short description of certain terminologies.

Perlman syndrome shares clinical overlaps with other overgrowth disorders, with similarities to Beckwith–Wiedemann syndrome and Simpson-Golabi-Behmel syndrome having been particularly emphasized in scientific study. Similarities with Beckwith-Wiedemann syndrome include polyhydramnios, macrosomia, nephromegaly and hypoglycaemia. It is the distinctive facial dysmorphology of Perlman, including deep-set eyes, depressed nasal bridge, everted upper lip, and macrocephaly which allows the two conditions to be distinguished from one another. Diagnosis of Perlman syndrome also overlaps with other disorders associated with Wilms tumor, namely, Sotos syndrome and Weaver syndrome.

Fetal warfarin syndrome (dysmorphism due to warfarin, warfarin embryopathy) is a condition associated with administration of warfarin during pregnancy.

Associated conditions include hypoplasia of nasal bridge, laryngomalacia, pectus carinatum, congenital heart defects, ventriculomegaly, agenesis of the corpus callosum, stippled epiphyses, telebrachydactyly, and growth retardation.

It is also known as "DiSaia syndrome". The symptoms are nasal hypoplasia, depressed nasal bridge, deep groove between nostril and nasal tip, stippling of uncalcified epiphyses during first year, mild hypoplasia of nails, shortened fingers, low birth weight, significant intellectual disability, seizures, reduced muscle tone, widely spaced nipples, deafness and feeding difficulty.

Perlman syndrome (PS) (also called renal hamartomas, nephroblastomatosis and fetal gigantism) is a rare overgrowth disorder present at birth. It is characterized by polyhydramnios and fetal overgrowth, including macrocephaly, neonatal macrosomia, visceromegaly, dysmorphic facial features, and an increased risk for Wilms' tumor at an early age. The prognosis for Perlman syndrome is poor and it is associated with a high neonatal mortality.

Robinow noted the resemblance of affected patients' faces to that of a fetus, using the term "fetal facies" to describe the appearance of a small face and widely spaced eyes. Clinical features also may include a short, upturned nose, a prominent forehead, and a flat nasal bridge. The upper lip may be "tented", exposing dental crowding, "tongue tie", or gum hypertrophy.

Though the eyes do not protrude, abnormalities in the lower eyelid may give that impression. Surgery may be necessary if the eyes cannot close fully. In addition, the ears may be set low on the head or have a deformed pinna.

Patients suffer from dwarfism, short lower arms, small feet, and small hands. Fingers and toes may also be abnormally short and laterally or medially bent. The thumb may be displaced and some patients, notably in Turkey, experience ectrodactyly. All patients often suffer from vertebral segmentation abnormalities. Those with the dominant variant have, at most, a single butterfly vertebra. Those with the recessive form, however, may suffer from hemivertebrae, vertebral fusion, and rib anomalies. Some cases resemble Jarcho-Levin syndrome or spondylocostal dysostosis.

Genital defects characteristically seen in males include a micropenis with a normally developed scrotum and testes. Sometimes, testicles may be undescended, or the patient may suffer from hypospadias. Female genital defects may include a reduced size clitoris and underdeveloped labia minora. Infrequently, the labia majora may also be underdeveloped. Some research has shown that females may experience vaginal atresia or haematocolpos.

The autosomal recessive form of the disorder tends to be much more severe. Examples of differences are summarized in the following table:

Porencephaly is a rare disorder. The exact prevalence of porencephaly is not known; however, it has been reported that 6.8% of patients with cerebral palsy or 68% of patients with epilepsy and congenital vascular hemiparesis have porencephaly. Porencephaly has a number of different, often unknown, causes including absence of brain development and destruction of brain tissue. With limited research, the most commonly regarded cause of porencephaly is disturbances in blood circulation, ultimately leading to brain damage. However, a number of different and multiple factors such as abnormal brain development or damage to the brain tissue can also affect the development of porencephaly.

The following text lists out potential risk factors of developing porencephaly and porencephalic cysts and cavities along with brief description of certain terminologies.

Cysts or cavities can occur anywhere within the brain and the locations of these cysts depend highly on the patient. Cysts can develop in the frontal lobe, parietal lobe, forebrain, hindbrain, temporal lobe, or virtually anywhere in the cerebral hemisphere.

Ballantyne syndrome has several characteristics:

- edema, always a key feature

- albuminuria of the mother, usually mild

- preeclampsia, unusual

The fetal symptoms are related to fluid retention, including ascites and polyhydramnios.

Fetal hydrops suggests the presence of an important and probably fatal fetal pathology.

It can be associated with twin-to-twin transfusion syndrome.

It is often a result of fetal alcohol syndrome (FAS) caused by large alcohol intake in the first month of pregnancy.

It can be associated with trisomy 13 which is also known as Patau syndrome, as well as hereditary neuralgic amyotrophy.

It can also be associated with fragile X syndrome and Prader-Willi syndrome.

Metopic synostosis, the early closure of metopic suture during skull development in children, can also cause hypotelorism.

Hypotelorism is a medical condition in which there is an abnormally decreased distance between two organs or bodily parts, usually pertaining to eyes (orbits), also known as orbital hypotelorism.

The problem of distinguishing (or not) between Ballantyne syndrome and preeclampsia is reflected in the diversity of terminology used and in the debate that surrounds the subject. It seems much more likely that an etiology of severe fetal hydrops may cause Ballantyne syndrome when the fetal status greatly worsens and that the syndrome is only a manifestation of the extreme severity of the fetus-placental pathology. Platelet count, aspartate transaminase, alanine transaminase, and haptoglobin are usually unaffected and may be used to distinguish mirror syndrome from HELLP syndrome.

Medical conditions include frequent ear infection, hearing loss, hypotonia, developmental problems, respiratory problems, eating difficulties, light sensitivity, and esophageal reflux.

Data on fertility and the development of secondary sex characteristics is relatively sparse. It has been reported that both male and female patients have had children. Males who have reproduced have all had the autosomal dominant form of the disorder; the fertility of those with the recessive variant is unknown.

Researchers have also reported abnormalities in the renal tract of affected patients. Hydronephrosis is a relatively common condition, and researchers have theorized that this may lead to urinary tract infections. In addition, a number of patients have suffered from cystic dysplasia of the kidney.

A number of other conditions are often associated with Robinow syndrome. About 15% of reported patients suffer from congenital heart defects. Though there is no clear pattern, the most common conditions include pulmonary stenosis and atresia. In addition, though intelligence is generally normal, around 15% of patients show developmental delays.

Minor physical anomalies (MPAs) are relatively minor (typically painless and, in themselves, harmless) congenital physical abnormalities consisting of features such as low-set ears, single transverse palmar crease, telecanthus, micrognathism, macrocephaly, hypotonia and furrowed tongue. While MPAs may have a genetic basis, they might also be caused by factors in the fetal environment: anoxia, bleeding, or infection. MPAs have been linked to disorders of pregnancy and are thought by some to be a marker for insults to the fetal neural development towards the end of the first trimester. Thus, in the neurodevelopmental literature, they are seen as indirect indications of inferferences with brain development.

MPAs have been studied in autism, Down syndrome, and in schizophrenia. A 2008 meta-analysis found that MPAs are significantly increased in the autistic population. A 1998 study found that 60% of its schizophrenic sample and 38% of their siblings had 6 or more MPAs (especially in the craniofacial area), while only 5% of the control group showed that many.

The most often cited MPA, high arched palate, is described in articles as a microform of a cleft palate. Cleft palates are partly attributable to hypoxia. The vaulted palate caused by nasal obstruction and consequent mouth breathing, without the lateralising effect of the tongue, can produce hypoxia at night.

Other MPAs are reported only sporadically. Capillary malformation is induced by RASA1 mutation and can be changed by hypoxia. A study in the American Journal of Psychiatry by Trixler et al.: found hemangiomas to be highly significant in schizophrenia. Exotropia is reported as having low correlation and high significance as well. It can be caused by perinatal hypoxia.

While not always pathological, it can present as a birth defect in multiple syndromes including:

- Catel–Manzke syndrome

- Bloom syndrome

- Coffin–Lowry syndrome

- congenital rubella

- Cri du chat syndrome

- DiGeorge's syndrome

- Ehlers-Danlos syndrome

- fetal alcohol syndrome

- Hallermann-Streiff syndrome

- Hemifacial microsomia (as part of Goldenhar syndrome)

- Juvenile idiopathic arthritis

- Marfan syndrome

- Noonan syndrome

- Pierre Robin syndrome

- Prader–Willi syndrome

- Progeria

- Russell-Silver syndrome

- Seckel syndrome

- Smith-Lemli-Opitz syndrome

- Treacher Collins syndrome

- Trisomy 13 (Patau syndrome)

- Trisomy 18 (Edwards syndrome)

- Wolf–Hirschhorn syndrome

- X0 syndrome (Turner syndrome)