A monstrous birth, variously defined in history, is a birth in which a defect of some sort renders the animal or human child monstrous. Such births were often taken as omens, signs of God, or moral warnings, but besides these supernatural or religious explanations, medical explanations were also given, in which often the mother's state of mind or her sexual behavior was responsible for the deformed fetus. In early and medieval Christianity, monstrous births posed difficult theological problems about humanity and salvation; in the early modern period the interest shifted toward scientific inquiry.

Dr. Lamaze was influenced by childbirth practices in the Soviet Union, which involved breathing and relaxation techniques under the supervision of a ""monitrice"", or midwife. The Lamaze method gained popularity in the United States after Marjorie Karmel wrote about her experiences in her 1959 book "Thank You, Dr. Lamaze", and with the formation of the American Society for Psycho prophylaxis in Obstetrics (ASPO Lamaze). Currently Lamaze International, founded by Karmel and Elisabeth Bing, is the premier childbirth education certifying organization in the world.

Modern Lamaze childbirth classes teach expectant mothers many ways to work with the labor process to reduce the pain associated with childbirth and promote normal (physiological) birth including the first moments after birth. Techniques include allowing labour to begin on its own, movement and positions, massage, aromatherapy, hot and cold packs, breathing techniques, the use of a "birth ball" (yoga or exercise ball), spontaneous pushing, upright positions for labour and birth, breastfeeding techniques, and keeping mother and baby together after childbirth. Each class has a specific curriculum that includes learning about common medical interventions and pain relief such as an epidural in an evidence based, non-biased manner.

The core beliefs of Lamaze International can be summarized with their Six Healthy Birth Practices. Each is heavily sourced from medical literature to provide sound evidence for the safest possible birth for baby and mother. These six practices are as follows:

1. Healthy Birth Practice 1: Let labor begin on its own

2. Healthy Birth Practice 2: Walk, move around and change positions throughout labor

3. Healthy Birth Practice 3: Bring a loved one, friend or doula for continuous support

4. Healthy Birth Practice 4: Avoid interventions that are not medically necessary

5. Healthy Birth Practice 5: Avoid giving birth on your back and follow your body's urges to push

6. Healthy Birth Practice 6: Keep mother and baby together - It's best for mother, baby and breastfeeding

Each of the above practices include a video, a patient handout, and professional references for medical personnel. The Lamaze Healthy Birth Practices are also available in eleven languages: English, Mandarin, Russian, Spanish, Portuguese, Czech, Polish, Romanian, Greek, Arabic, and Hebrew.

A mooncalf (or moon-calf) is a monstrous birth, the abortive fetus of a cow or other farm animal. The term was occasionally applied to an abortive human fetus.

The term derives from the once widespread superstition, present in many European folk traditions, that such malformed creatures were the product of the sinister influence of the Moon on fetal development.

Polycephaly is the condition of having more than one head. The term is derived from the Egyptian stems "poly" (Greek: "πολύ") meaning "many" and "kephalē" (Greek: "κεφάλη") meaning "head". A polycephalic organism may be thought of as one being with a supernumerary body part, or as two or more beings with a shared body.

Two-headed animals (called bicephalic or dicephalic) and three-headed (tricephalic) animals are the only type of multi-headed creatures seen in the real world, and form by the same process as conjoined twins from monozygotic twin embryos.

In humans, there are two forms of twinning that can lead to two heads being supported by a single torso. In dicephalus parapagus dipus, the two heads are side by side. In craniopagus parasiticus, the two heads are joined directly to each other, but only one head has a functional torso. Survival to adulthood is rare, but does occur in some forms of dicephalus parapagus dipus.

There are many occurrences of multi-headed animals in mythology. In heraldry and vexillology, the double-headed eagle is a common symbol, though no such animal is known to have ever existed.

Two-headed people and animals, though rare, have long been known to exist and documented.

A woman's risk of having a baby with chromosomal abnormalities increases with her age. Down syndrome is the most common chromosomal birth defect, and a woman's risk of having a baby with Down syndrome is:

- At age 20, 1 in 1,441

- At age 25, 1 in 1,383

- At age 30, 1 in 959

- At age 35, 1 in 338

- At age 40, 1 in 84

- At age 45, 1 in 32

- At age 50, 1 in 44

In terms of ovarian reserve, a typical woman has 12% of her reserve at age 30 and has only 3% at age 40. 81% of variation in ovarian reserve is due to age alone, making age the most important factor in female infertility.

The most common methods of checking the status of the ovarian reserve is to perform a blood test on day 3 of the menstrual cycle to measure serum FSH level, alternatively a blood test to measure the serum AMH level can give similar information. Transvaginal ultrasound can also be used to “count the number of follicles” and this procedure is called Antral Follicle Count.

The American College of Obstetricians and Gynecologists recommends ovarian reserve testing should be performed for women older than 35 years who have not conceived after 6 months of attempting pregnancy and women at higher risk of diminished ovarian reserve, such as those with a history of cancer treated with gonadotoxic therapy, pelvic irradiation, or both; those with medical conditions who were treated with gonadotoxic therapies; or those who had ovarian surgery for endometriomas.

It is important to recognize that a poor result from ovarian reserve testing does not signify an absolute inability to conceive and should not be the sole criterion considered to limit or deny access to infertility treatment.

A woman's fertility peaks lasts during the twenties and first half of thirties, after which it starts to decline, with advanced maternal age causing an increased risk of female infertility.

According to Henri Leridon, PhD, an epidemiologist with the French Institute of Health and Medical Research, of women trying to get pregnant, without using fertility drugs or in vitro fertilization:

- At age 30

- 75% will have a conception ending in a live birth within one year

- 91% will have a conception ending in a live birth within four years.

- At age 35

- 66% will have a conception ending in a live birth within one year

- 84% will have a conception ending in a live birth within four years.

- At age 40

- 44% will have a conception ending in a live birth within one year

- 64% will have a conception ending in a live birth within four years.

Because postmortem fetal extrusion is so rare, and occurs under highly idiosyncratic conditions regarding the individual and the ambient environment, this phenomenon has not been studied for possible applications to forensic investigation. Even if the study of postmortem fetal extrusion could lead to improved investigative methods, experimental research would be highly problematic. At present, forensic scientists have at their disposal an array of established techniques and procedures for a death investigation at the stages of decomposition when postmortem fetal extrusion typically occurs.

In archaeology, the study of mortuary context, that is, the interpretation of the postmortem treatment of the dead, whether an individual or as pertains to patterns within a group, has led to the development of hypotheses on social status and/or hierarchy regarding many cultures, ancient and extant. In addition, the determination of whether or not delivery actually occurred prior to death has a bearing on analyses of the mother's population, as the concentration of trace elements differ markedly between the skeletons of prepartum adult women (before giving birth) and women who are lactating; the identification of coffin birth would lead to more accurate analyses of the number of lactating women in a population or the rate of maternal mortality. It is therefore necessary for investigators to be able to recognize postmortem fetal extrusion when encountered in an excavated burial.

The risk of pregnancy complications increases as the mother's age increases. Risks associated with childbearing over the age of 50 include an increased incidence of gestational diabetes, hypertension, delivery by caesarean section, miscarriage, preeclampsia, and placenta previa. In comparison to mothers between 20 and 29 years of age, mothers over 50 are at almost three times the risk of low birth weight, premature birth, and extremely premature birth; their risk of extremely low birth weight, small size for gestational age, and fetal mortality was almost double.

Facts about the conception of pregnancies in this age group can be difficult to determine, but they are nearly always due to the use of IVF with donor eggs.

Postmortem fetal extrusion can be very difficult to recognize once a body has undergone complete skeletonization, and bioarchaeologists are often very cautious about asserting the presence of this phenomenon. There are numerous cultural reasons why a mother and an infant might be interred together, so the joint presence of neonatal remains and an adult female is not taken as conclusive evidence of postmortem fetal extrusion; however, there have been excavated burials where the position of a set of fetal remains relative to those of an adult female supported this hypothesis. There are a few general guidelines when an archaeologist is assessing the placement of the fetus and the adult:

1. If the fetal remains are found in a fetal position and are wholly within the pelvic cavity of the adult, the fetus died and was interred prior to delivery. The pregnant woman may therefore have died due to labor complications.

2. If the infant is found alongside the adult, with the head oriented in the same direction as the adult, then the infant was delivered, whether naturally or by caesarian incision, around the time of death, and thereafter interred.

1. Delivered infants have also been interred between or alongside the tibiae (shins), but the infant is still oriented in the same direction as the adult.

2. If the majority of the fetal remains are in the pelvic cavity of the adult, yet the legs are extended and/or the cranium lies among the ribs, then the infant may have been delivered and then placed on top of the mother's torso prior to burial. As both bodies skeletonized, the infant's bones would have settled among the mother's ribs and vertebrae.

3. If the fetal remains are complete and in a position inferior to and in-line with the pelvic outlet, with the head oriented opposite to that of the mother (toward the foot of the coffin or grave), then there is the possibility of coffin birth.

1. Evidence for postmortem fetal extrusion may be less ambiguous when the fetal remains are found to lie within the pelvic outlet of the adult, thus indicating that partial extrusion had occurred during decomposition.

In 1975, it was reported that during the excavation of a medieval cemetery in Kings Worthy, England, fetal remains appeared to lie within the birth canal of the skeleton of a young woman, with the fetal cranium external to the pelvic outlet and between the two femora (thigh bones) and the fetal leg bones clearly within the pelvic cavity. Other cases of coffin birth at archaeological sites have been described, such as in 1978 at a Neolithic site in Germany, at a medieval site in Denmark in 1982, and in 2009 at an Early Christian period site at Fingal, Ireland. A coffin birth was also described in a 2011 episode of the BBC show "History Cold Case", featuring the Roman era remains of a woman and three neonates discovered near Baldock, Hertfordshire. Another was identified in 2006 in a 14th-century Black Death cemetery in Genoa, Italy.

A specific fear of clowns has sometimes been discussed in terms of a specific phobia. The term "" is a neologism coined in the context of informal ""-phobia" lists".

The term is not listed in the World Health Organisation's ICD-10 nor in the American Psychiatric Association's DSM-5 categorization of disorders.

A study of a population of French women from 1670 and 1789 shows that those who married at age 20–24 had 7.0 children on average and 3.7% remained childless. Women who married at age 25–29 years had a mean of 5.7 children and 5.0% remained childless. Women who married at 30–34 years had a mean of 4.0 children and 8.2% remained childless. The average age at last birth in natural fertility populations that have been studied is around 40.

In 1957, a study was done on a large population (American Hutterites) that never used birth control. The investigators measured the relationship between the age of the female partner and fertility. (Infertility rates today are believed to be higher in the general population than for the population in this study from the 1950s.)

This 1957 study found that:

- By age 30, 7% of couples were infertile

- By age 35, 11% of couples were infertile

- By age 40, 33% of couples were infertile

- At age 45, 87% of couples were infertile

Patients with a double uterus may need special attention during pregnancy as premature birth and malpresentation are common. Cesarean section was performed in 82% of patients reported by Heinonen.

Uterus didelphys, in certain studies, has also been found associated with higher rate of infertility, miscarriage, intrauterine growth retardation, and postpartum bleed.

An early reference to monstrous birth is found in the apocalyptic biblical text 2 Esdras, where it is linked to menstruation: "women in their uncleanness will bear monsters." Monstrous births are often placed in a religious context and interpreted as signs and symbols, as is evidenced in the 1493 "Nuremberg Chronicle". According to David Hume's "The Natural History of Religion", they are among the first signs that arouse the barbarian's interest. Monstrous human births raise the question of the difference between humans and animals, and anthropologists have described different interpretations of and behaviors toward such births. Among the East African Nuer people, monstrous births are acted on in a way that restores the division between the categories of human and animal: "the Nuer treat monstrous births as baby hippopotamuses, accidentally born to humans, and, with this labelling, the appropriate action is clear. They gently lay them in the river where they belong."

Whether monstrous births were natural, unnatural, or supernatural remained a topic of discussion. Saint Augustine held that nothing "done by the will of God could be contrary to nature," whereas Thomas Aquinas considered some miracles to be against nature.

In twin pregnancies, it is very common for one or both babies to be in the breech position. Most often twin babies do not have the chance to turn around because they are born prematurely. If both babies are in the breech position and the mother has gone into labour early, a cesarean section may be the best option. About 30-40% of twin pregnancies result in only one baby being in the breech position. If this is the case, the babies can be born vaginally. After the first baby who is not in the breech position is delivered, the baby who is presented in the breech position may turn itself around, if this does not happen another procedure may performed called the breech extraction. The breech extraction is the procedure that involves the obstetrician grabbing the second twin's feet and pulling him/her into the birth canal. This will help with delivering the second twin vaginally. However, if the second twin is larger than the first, complications with delivering the second twin vaginally may arise and a cesarean section should be performed. At times, the first twin (the twin closest to the birth canal) can be in the breech position with the second twin being in the cephalic position (vertical). When this occurs, risks of complications are higher than normal. In particular, a serious complication known as Locked twins. This is when both babies interlock their chins during labour. When this happens a cesarean section should be performed immediately.

Turning the baby, technically known as external cephalic version (ECV), is when the baby is turned by gently pressing the mother’s abdomen to push the baby from a bottom first position, to a head first position. ECV does not always work, but it does improve the mother’s chances of giving birth to her baby vaginally and avoiding a cesarean section. The World Health Organisation recommends that women should have a planned cesarean section only if an ECV has been tried and did not work.

Women who have an ECV when they are 36–40 weeks pregnant are more likely to have a vaginal delivery and less likely to have a cesarean section than those who do not have an ECV. Turning the baby before this time makes a head first birth more likely but ECV before the due date can increase the risk of early or premature birth which can cause problems to the baby.

There are treatments that can be used which might affect the success of an ECV. Drugs called beta-stimulant tocolytics help the woman’s muscles to relax so that the pressure during the ECV does not have to be so great. Giving the woman these drugs before the ECV improves the chances of her having a vaginal delivery because the baby is more likely to turn and stay head down. Other treatments such as using sound, pain relief drugs such as epidural, increasing the fluid around the baby and increasing the amount of fluids to the woman before the ECV could all effect its success but there is not enough research to make this clear.

Turning techniques mothers can do at home are referred to Spontaneous Cephalic Version (SCV), this is when the baby can turn without any medical assistance. Some of these techniques include; a knee to chest position, the breech tilt and moxibustion, these can be performed after the mother is 34 weeks pregnant. Although there is not a lot of evidence to support how well these techniques work, it has worked for some mothers.

Obstetric ultrasound has become useful in the assessment of the cervix in women at risk for premature delivery. A short cervix preterm is undesirable: A cervical length of less than 25 mm at or before 24 weeks of gestational age is the most common definition of cervical incompetence.

Fetal fibronectin (fFN) has become an important biomarker—the presence of this glycoprotein in the cervical or vaginal secretions indicates that the border between the chorion and deciduas has been disrupted. A positive test indicates an increased risk of preterm birth, and a negative test has a high predictive value. It has been shown that only 1% of women in questionable cases of preterm labor delivered within the next week when the test was negative.

A pelvic examination will typically reveal a double vagina and a double cervix. Investigations are usually prompted on the basis of such findings as well as when reproductive problems are encountered. Not all cases of uterus didelphys involve duplication of the cervix and vagina.

Helpful techniques to investigate the uterine structure are transvaginal ultrasonography and sonohysterography, hysterosalpingography, MRI, and hysteroscopy. More recently 3-D ultrasonography has been advocated as an excellent non-invasive method to evaluate uterine malformations.

Uterus didelphys is often confused with a complete uterine septum. Often more than one method of investigation is necessary to accurately diagnose the condition. Correct diagnosis is crucial as treatment for these two conditions is very different. Whereas most doctors recommend removal of a uterine septum, they generally concur that it is better not to operate on a uterus didelphys. In either case, a highly qualified reproductive endocrinologist should be consulted.

Craniopagus twins are conjoined twins that are fused at the cranium. This condition occurs in about 10–20 babies in every million births in the United States. Among this small group, cephalic conjoining, or craniopagus twinning, represents the rarest of congenital abnormalities, accounting for 2–6% of all conjoined twins. Additionally, conjoined twins are genetically identical and always share the same sex. The union in craniopagus twins may occur on any portion of the Calvary, but does not include either the face or the foramen magnum. The thorax and abdomen are separate and each twin has its own umbilicus and umbilical cord. The union may involve the entire diameter of the head or only a small portion. This suggests that although there are many different kinds of vulnerabilities already known in the scientific community, there are an infinite number of variations that can occur. Most of these variations are based on the rotation of one twin's skull to the other and the different phenotype sub-groups of craniopagus twins are based on all these rotational conformations. Each of these factors (rotation, spot of union) affects the development of the brain, the vascular system within the brain and overall wellness of life both of the twins have outside the womb. Relatively few craniopagus twins survive the perinatal period – approximately 40% of conjoined twins are stillborn and an additional 33% die within the immediate perinatal period, usually from organ abnormalities and failure. However 25% of craniopagus twins survive and can be considered for a surgical separation and several attempts occur yearly worldwide. In the last-half century, many advances in medicine including brain imaging, neuro-anesthesia and neurosurgical techniques have proven that a successful outcome is possible following separation of total craniopagus twins.

Acrotomophiles may be attracted to amputees because they like the way they look or they may view the amputee’s stump as a phallic object which can be used for sexual pleasure.A small number of Acrotomophiles may enjoy the idea of dominating the amputee during couples play and they may also become aroused with the thought of having to take care of an amputee.

Some studies show that the probability of premature birth is roughly 1% higher for women who smoke during pregnancy going from around -1% to 1%.