Two in a Dark Womb Trivia Quiz

Answer: 37 weeks

Full-term single pregnancies can last from 38 to 42 weeks. However, due to the limited space in the mother's womb, twin pregnancies usually are shorter. The average length of pregnancy has been shown to be about 37 weeks for twins. Despite the shorter gestation period, newborns are able to survive.

In fetal development, the lungs start to be functional at around 24 weeks' gestation; therefore, a newborn can potentially survive if born at that time.

Answer: They have different genetic makeups and therefore are no different from non-twin siblings

As opposed to identical twins, fraternal twins come from two different eggs, fertilized by two different sperm. Therefore, they have different genetic makeups, the same as siblings born years apart. As the sexes of the twins is also determined randomly, they may be of either gender or of the same gender; the most common result is one male and one female. Fraternal twins are also known (scientifically) as dizygotic twins, meaning they are formed from two zygotes (fertilized eggs).

Answer: 2

The two zygotes implant themselves in different places in the uterus, therefore forming separate placentas. Twins sharing the same placenta are known as "monochorionic", while those having separate placentas are called "dichorionic".

Answer: Monozygotic twins

"Monozygotic" means that the fetuses are derived from a single fertilized egg. "Dizygotic" is the scientific term for fraternal twins.

Answer: The blastocyst randomly splits into two separate organisms

About five days after fertilization the organism is composed of about 70-100 cells and is called a blastocyst. At this point, it implants itself into the uterus. In the case of identical twins, the blastocyst shortly thereafter collapses into two separate blastocysts with the same genetic material. From there, two embryos develop.

Answer: 1

In most cases, identical twins are formed after the original blastocyst has implanted itself into the wall of the uterus. Therefore, the twins are connected through two umbilical cords to the same placenta. Occasionally, the blastocyst splits into two before implantation, therefore winding up with implantation into two separate places in the uterus, and two placentas.

Answer: True

Depending on exactly when the blastocyst separates into two, the twins may develop in separate amniotic sacs or the same one. Typically, if it splits by the eighth day after fertilization, there will be two sacs; any time after that, there will most likely be only one sac. Development in the same amniotic sac is called "monoamniotic", while two sacs is called "diamniotic". Development in one sac can cause complications, such as entanglement of the umbilical cords and one twin developing more slowly than the other.

The survival rate of monoamniotic twins is only 50-60%.

Answer: Eye color

Since eye color is a trait that is determined by genetics, identical twins, who share the same genetic material, will always have the same colored eyes. Birth weights can vary, depending on how the twins developed in the womb. Fingerprints and the shape of the belly button are determined randomly.

Answer: A twin that dies early in the pregnancy

Vanishing twins can occur in either fraternal or identical twin pregnancies. For whatever reason, one of the twins dies in utero, and is then either excreted in a similar manner to menstrual fluid, absorbed by the other twin, or stillborn. It is often detected by ultrasound, where there are two fetuses present early in the pregnancy, but a later ultrasound reveals only one fetus.

It can also occur when, by using in vitro fertilization, two babies are planned but only one survives.

Answer: Almost all conjoined twins are stillborn

Conjoined twins are usually fused at the middle of the body, while some are fused at the head. There are two theories as to what causes them; the more accepted theory today is that they are formed when separated twins fuse together when their stem cells are searching for other stem cells, whereas the older theory suggested that the blastocyst simply failed to separate completely. Conjoined twins usually result when a blastocyst separates 12 days after fertilization or later. About 50% of them are stillborn.