Miscarriages usually occur before 20 weeks gestation. Many people wonder what are the main causes of this early gestational loss. However, it is important to define well the concept of miscarriage and to understand it.
Spontaneous abortion is considered to be the loss of pregnancy before the fetus is able to survive safely outside the mother's uterus. Between 8% and 15% of the pregnancies that are detected end in this way. The causes of miscarriages are not well understood. However, most of them occur when a pregnancy is not developing normally and there is usually nothing the woman or her doctor can do to prevent it.
In any case, among the most frequent reasons for miscarriage we can find genetic, immunological, anatomical and endocrine causes.
Provided below is an index with the 8 points we are going to expand on in this article.
- 1.
- 2.
- 3.
- 3.1.
- 3.2.
- 3.3.
- 3.4.
- 4.
- 5.
- 5.1.
- 5.2.
- 5.3.
- 5.4.
- 5.5.
- 6.
- 7.
- 8.
Why do miscarriages occur?
Miscarriage is also known as spontaneous abortion or miscarriage. This gestational loss usually occurs before the 20th week of pregnancy. Pregnancy loss after this week would be considered an intrauterine fetal death.
The causes of miscarriages are not known exactly, but they are divided into fetal and maternal causes.
In the case of the fetus, the reasons for stopping the pregnancy are alterations at the chromosomal level that prevent fetal development. In contrast, maternal causes of miscarriage are usually related to autoimmune problems, endocrine problems, infections or anatomical alterations.
Each of these possible causes of miscarriage is detailed in the following sections.
Genetic causes in the fetus
Chromosomal abnormalities in the fetus are very common, so that more than 50% of miscarriages that occur during the first trimester of pregnancy are caused by chromosomal problems in the fetus.
Chromosomes are the tiny filament-like cellular structures where genes are located. Each person has 23 pairs of chromosomes, or 46 chromosomes in total. Of each pair, one chromosome comes from the father and the other from the mother.
A large number of these chromosomal abnormalities are the result of a defective egg or sperm that has either too many or too few chromosomes. The resulting embryo has an incorrect number of chromosomes, which usually leads to miscarriage because it is not able to continue its development.
Chromosomal abnormalities become more common as a woman's age increases, as does the risk of miscarriage. Most of these chromosomal alterations are numerical, mainly trisomies and, to a lesser degree, triploidies.
These types of genetic alterations in the fetus usually cause hatching eggs and very early miscarriages before the eighth week of pregnancy.
Maternal causes of miscarriage
Another reason why a miscarriage may occur in the first trimester of pregnancy are maternal causes, whether due to immunological, anatomical, physiological or even infectious alterations.
The following sections describe each of them in detail.
Immunological causes
These are the most frequent causes of repeated miscarriages. In most cases it is due to an incompatibility of the mother and the embryo due to immunological similarities between the couple. This causes the mother to reject the embryo.
It can also happen that the mother generates antibodies against her own body and causes thrombosis or placental vascular occlusions that can lead to miscarriages.
If you are interested in this topic, we recommend you to continue reading the following article: Immunological infertility: types, causes and treatments.
Anatomical causes
Among the most frequent anatomical causes leading to miscarriages are congenital anomalies of the uterus and cervical incompetence.
In the case of congenital anomalies of the uterus, they are associated with problems present from birth. This is what happens in women who have a septate uterus or the so-called"double uterus".
In contrast, cervical incompetence occurs when the internal orifice of the cervix is dilated and prevents the embryo from being retained. Dilatation of the cervix is the most common reason for miscarriage due to a maternal cause. Only with a uterine x-ray can the state of the cervix be known and thus be able to take precautions during pregnancy, so it has a good prognosis.
Physiological or endocrine causes
The physiological causes of spontaneous abortions are related to the so-called progesterone insufficiencyo corpus luteum insufficiency.
Maintenance of gestation until 8-9 weeks of pregnancy depends on adequate production of progesterone by the corpus luteum. Thus, if this hormone decreases, an inhibition of the correct nesting of the embryo may occur.
This group includes miscarriages caused by poorly controlled diabetes, thyroid disorders or polycystic ovary syndrome.
Infections and other causes
Some of the infections that can cause sporadic abortion are acute infections due to cytomegalovirus, chlamydias, mycoplasmas, etc. Specific infections due to syphilis, listeriosis and similar can also cause miscarriages.
On the other hand, the use of intrauterine devices (IUDs) as a contraceptive method, in many cases, can cause uterine infections that are difficult to control.
In addition to these clinical factors, the risk of miscarriage is also influenced by the mother's lifestyle lifestyle of the mother. Thus, women who drink alcohol, smoke or use drugs may be at a higher risk of having a miscarriage. Overweight in the mother also has a negative effect on the correct evolution of the pregnancy.
For all these reasons, it is of vital importance that a woman takes care of herself from the moment she intends to become pregnant, so that many of the problems, even in the quality of her egg, will be reduced. It should be noted that the partner, who contributes half of the genetic load, should also take care before pregnancy, avoiding tobacco, drugs or alcohol.
How to prevent miscarriages?
In most cases there is no way to prevent this gestational loss. It is simply necessary to pay special attention to both the mother's and the baby's health. For this reason, it will be essential to attend regular pregnancy check-ups. In addition, it is always recommended to avoid smoking and drinking alcohol, along with limiting caffeine consumption.
Sometimes specialists advise the intake of a vitamin complex at the beginning of pregnancy depending on each situation. It is also good practice to try to reduce stress levels and eat a calcium-rich diet.
FAQs from users
Why do miscarriages occur?
There are different causes of miscarriage, but most of them are caused by faults in the genetic information of the embryo, either because one of the two gametes (egg or sperm) has some alteration, or because a genetic error occurs during the cellular multiplication of embryonic development.
Does uterine prolapse affect pregnancy?
Genital prolapse is the exit or herniation of one or more pelvic organs through the vaginal wall and external genitalia. Its frequency in reproductive ages is lower, since it is usually a more common pathology in menopause. Risk factors have been widely recognized as possible causes: multiparity, obstetric trauma, prolonged expulsive periods, obesity, sacro-nervous lesions, chronic pneumopathies, estrogen deficiency, etc.
Uterine prolapse in a young woman coinciding with pregnancy is an almost exceptional occurrence since only 233 cases had been reported up to 1968. Most of the cases reported in the literature occurred in the years prior to 1970, so that the modernization of obstetrics in recent years has made this situation even rarer today.
The main complications of uterine prolapse during pregnancy are miscarriage (15-21%), threatened preterm labor (18%), pelvic pain, leucorrhea, uterine incarceration, urinary retention, and increased urinary tract infections.
What are the causes of repeated biochemical pregnancies?
A biochemical pregnancy is an early pregnancy loss that occurs shortly after implantation.
The exact cause of a biochemical pregnancy is unknown. But in most cases miscarriage is due to problems with the embryo, possibly caused by poor quality sperm or eggs.
Read more
Can the causes of miscarriages be prevented?
Normally, miscarriages cannot be prevented since this type of gestation is stopped by an abnormality. However, it is true that there are some measures that reduce the risk of miscarriage.
These are measures such as avoiding smoking, alcohol and blows to the abdomen. In addition, it is always advisable to lead a healthy lifestyle and follow all the recommendations established by specialists.
What are the complications of miscarriages?
In principle, if the gestational loss is detected in time, it does not usually result in serious complications for the woman. However, on occasion, hemorrhage, genital infections, small leaks, etc., may occur.
Suggested for you
Although a miscarriage is the loss of the baby before the 20th week, there are several types of miscarriages. For more information, we recommend you visit the following article: Types of miscarriage: How many are there and how do they differ?
On the other hand, if you are interested in knowing if abortions have consequences on a woman's fertility, you can visit this link: Fertility after abortion: Is pregnancy possible?
We make a great effort to provide you with the highest quality information.
🙏 Please share this article if you liked it. 💜💜 You help us continue!
References
Adam J Devall, Arri Coomarasamy. Sporadic pregnancy loss and recurrent miscarriage. Best Pract Res Clin Obstet Gynaecol. 2020 Nov;69:30-39 (ver)
Andrea M F Woolner, Priti Nagdeve, Edwin-Amalraj Raja, Siladitya Bhattacharya 1, Sohinee Bhattacharya. Family history and risk of miscarriage: A systematic review and meta-analysis of observational studies. Acta Obstet Gynecol Scand. 2020 Dec;99(12):1584-1594 (ver)
Ashley Redinger, Hao Nguyen. Incomplete Abortions. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan.2021 Jul 4 (ver)
Beatriz Guerrero, Fakhri Hassouneh, Elena Delgado, Javier G Casado, Raquel Tarazona. Natural killer cells in recurrent miscarriage: An overview. J Reprod Immunol. 2020 Nov;142:103209. doi: 10.1016/j.jri.2020.103209 (ver)
Evdokia Dimitriadis, Ellen Menkhorst, Shigeru Saito, William H Kutteh, Jan J Brosens. Recurrent pregnancy loss. Nat Rev Dis Primers. 2020 Dec 10;6(1):98. doi: 10.1038/s41572-020-00228-z.
Mauro Cozzolino, Juan Antonio García-Velasco, Marcos Meseguer, Antonio Pellicer, Jose Bellver. Female obesity increases the risk of miscarriage of euploid embryos. Fertil Steril. 2021 Jun;115(6):1495-1502.
FAQs from users: 'Why do miscarriages occur?', 'Does uterine prolapse affect pregnancy?', 'What are the causes of repeated biochemical pregnancies?', 'Can the causes of miscarriages be prevented?' and 'What are the complications of miscarriages?'.
Authors and contributors
