The three biggest risks to fetal development are placental problems, lifestyle factors and maternal health conditions.
Placental problems like placenta abruption or placenta previa can interfere with delivery and pregnancy and fetal development.
Lifestyle factors such as exposure to toxins, substance use and smoking can lead to risks to the developing fetus and maternal health conditions such as high blood pressure and diabetes can also cause risks to fetal development and affect the baby's development.
A fetus can get sick in the womb although in most cases if you're sick with the flu or cold yourself as a pregnant mother the baby or fetus will often be fine.
Although fever from an infection such as the flu early in pregnancy is linked to possible birth defects.
The placenta acts as a barrier to some infections, although certain infections can still pass to the fetus and cause complications or even death to the fetus.
Many cold medicines that a pregnant mother takes can also potentially harm the fetus.
And other infections can cause the fetus to get sick and even lead to miscarriages or birth defects.
Some infections that can harm a fetus are the Zika virus, rubella and cytomegalovirus or CMV.
These infections can lead to and cause a variety of birth defects, developmental delays and other possible health issues in the fetus and infant.
CMV or cytomegalovirus is a common viral infection which can cause congential CMV in newborns and lead to hearing loss, developmental delays and other possible birth defects.
Rubella, which is also called the German measles, can cause severe birth defects if it's contracted during the first trimester of pregnancy, including heart defects, hearing loss, neurological defects and eye abnormalities.
Zika virus infections during pregnancy can lead to microcephaly, which is a small head size due to abnormal brain development, eye abnormalities and other developmental problems.
Other infections which can harm the fetus are Listeria, Syphilis and Toxoplasmosis, parvovirus B19 and monocytogenes
Even genital herpes can be transmitted to the baby during vaginal delivery.
Common bacteria that can cause miscarriage are bacterial vaginosis, Chlamydia and Gonorrhea, Syphilis, and other bacteria such as Anaerobacillus, Cutibacterium, Microbacterium, microbacterium and Streptococcus.
A woman's vaginal microbiome plays a critical role in maintaining a healthy environment for pregnancy and having an imbalance in the vaginal microbiome, which is seen in bacterial vaginosis or BV, can disrupt the balance and increase the risk of miscarriage.
Bacteria can also trigger inflammation in the uterus and can affect the viability of the fetus or embryo.
And some bacterial infections such as Listeriosis can directly affect the baby and lead to miscarriage and certain bacteria can also compromise the cervical tissues and cause the cervix to weaken and dilate prematurely and lead to miscarriage.
Weak sperm or poor quality sperm can also cause a miscarriage.
Weak or damaged sperm can affect the ability of the sperm to fertilize an egg and even if the fertilization of the egg does occur, it can also disrupt the early embryo development and increase the risk of miscarriage.
Having multiple miscarriages is thought to be linked to the poor quality of a male's sperm.
The most common week to miscarry is during the 7th week of gestation although the miscarriages can also occur between 6 weeks to 8 weeks gestation and most miscarriages happen before 10 weeks.
Miscarriages are actually pretty common and at least one in five pregnancies result in miscarriages and as many as one in four early pregnancies result in miscarriages.
The reason why most miscarriages happen at 7 weeks is because of chromosomal abnormalities in the developing fetus.
Chromosomal abnormalities in the developing fetus prevent the fetus from developing properly and the abnormalities can lead to the inability of the fetus to survive which leads to the miscarriage.
Other factors that can cause miscarriages include infections, smoking or drug use and even uterine abnormalities.
The development of the antibodies against H-Y antigens is also thought to be a contributing factor to the increased risk of miscarriage in any subsequent pregnancies, especially if the fetus is also a male fetus.
A significant portion of early miscarriages are a result of chromosomal problems in the fetus.
And older mothers are also slightly at higher risk for miscarriages.
And even some genetic predispositions can also increase the woman's risk of miscarriage.
Other factors that can result in miscarriage include stress, drug use, smoking and excessive alcohol consumption.