Causes of post-term pregnancy
A whole complex of maternal and fetoplacental factors can prevent the timely onset of labor. The key roles in the etiology are played by the following pathological shifts:
- Endocrine disorders. There is a decrease in the overall estrogen pool in the maternal body and a pronounced imbalance of their fractions. Concurrently, a relative predominance of progesterone (the hormone of the corpus luteum) occurs, which inhibits the onset of labor.
- Tissue factors. Profound metabolic changes occur in the muscular layer of the uterus (myometrium). These shifts significantly reduce the contractile capacity of the uterine musculature.
- Vascular-placental pathology. Chronic impairment of uteroplacental blood flow, as well as the presence of gestosis (specifically, preeclampsia), negatively affects the mechanisms triggering labor.
- Immune and genetic factors. Hereditary predisposition to post-term pregnancy and a general immunological imbalance in the mother's body are of considerable importance.
Phenotypic and anthropometric features
Diagnosis of post-term status is based on a thorough assessment of the infant's physical development and skin condition immediately after birth.
Anthropometry
Most often, the body weight and length of a post-term child exceed the normal parameters of full-term infants (development of macrosomia). However, in some cases, paradoxically low body weight is observed. Such a picture indicates a severe pathological course of pregnancy, for example, against the background of pronounced placental insufficiency.
Appearance and skin
- Vernix caseosa is either completely absent or its amount is drastically reduced.
- The skin appears flabby and is prone to peeling (desquamation).
- Due to the intrauterine passage of meconium, the skin often acquires a characteristic yellowish or greenish tint.
- Maceration of the hands and feet is noted (so-called "washerwoman's" palms and soles).
- The nail plates are noticeably elongated.
Bone and cartilage system
The cranial bones of a post-term child are densified, and the cranial sutures and fontanelles are significantly narrowed. The cartilages of the nose and auricles are also distinguished by increased density. During X-ray examination, ossification centers are determined in the proximal epiphyses of the tibia and humerus.
Adaptation features and consequences
The process of transition to extrauterine life in post-term children proceeds more complexly and takes longer than in infants born on time.
- Early neonatal adaptation. Physiological weight loss in the first days of life is significantly more pronounced. At the same time, the process of restoring the initial weight takes much longer.
- Morbidity in the first year. The risk of developing various pathologies in such children increases by 2–2.7 times. Neurological disorders, rickets, and anemia dominate the morbidity structure.
- Prognosis. Neonatal and early perinatal mortality rates are in direct dependence on how long the post-term pregnancy lasted. The most unfavorable scenario for the child's life and health is the combination of true post-term status with intrauterine growth restriction syndrome.
Image of an "old man from the bathhouse": skin is flabby and peeling ("old man"), palms and soles are shriveled ("bathhouse"), no vernix (washed off), and nails are long.
Class and exam questions
Why might a post-term child have low rather than high weight?
Paradoxically low anthropometric parameters in a post-term child are usually associated with the pathological course of pregnancy, primarily with the development of placental insufficiency, due to which the fetus does not receive sufficient nutrients.
How does the skin change in post-term pregnancy?
Vernix caseosa disappears, the skin becomes flabby and peels. Maceration of the feet and hands ("washerwoman's" feet) is frequently observed, as well as a greenish or yellowish tint due to the passage of meconium.
What are the main health risks for a post-term child in the first year of life?
The risk of morbidity increases by 2–2.7 times compared to full-term infants. The most characteristic problems are neurological disorders, the development of anemia, and rickets.
What else to study on this topic
- Mechanisms of endocrine imbalance formation (estrogens and progesterone) in post-term pregnancy
- Pathogenesis of metabolic shifts in the myometrium
- Influence of uteroplacental blood flow on fetal development
- Intrauterine growth restriction syndrome combined with post-term pregnancy
- X-ray diagnostics of ossification centers in newborns
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