✅ PERIODO FETAL | DESDE LA NOVENA SEMANA AL NACIMIENTO [2023] 📚 EMBRIOLOGÍA HUMANA | RESUMEN

Periodo Fetal: Development Overview

The video discusses the fetal period, focusing on morphological and functional changes from the ninth week until birth.

Morphological Changes

• In the third month (9th to 12th week), the fetus's head size decreases while facial features become more human-like. Limbs develop proportionally, and primary ossification centers appear in bones by week 12.

• By the fourth month (13th to 16th week), there is a significant decrease in head-body proportion, accelerated growth of lower limbs, and blood-forming function peaks in the spleen.

Functional Developments

• Endocrine activity starts in glands like thyroid and pituitary at nine weeks. By week 10, the liver begins erythropoietic function followed by bilirubin production two weeks later. Hematopoietic activity initiates in bone marrow by the end of week 12.

• During the fifth month (17th to 20th week), slower growth occurs with proportional lower limb development. Vernix caseosa secretion forms, subcutaneous brown fat develops for heat production, and fetal movements are perceivable by the mother.

Importance of Fetal Measurements

Understanding fetal age through measurements aids in proper pregnancy care and anomaly detection.

• Fetal age estimation using measurements like fetal length (LCC or LVT) and weight is crucial for monitoring pregnancy, especially for mothers with narrow pelvises or assessing fetal development.

Desarrollo Fetal: Meses 7 a 9

This section discusses the fetal development from the seventh to ninth month of pregnancy, focusing on both functional and morphological changes.

Development in the Seventh Month

• The adrenal gland starts functioning.

• Sucking reflex is noticeable.

• Fetus can perceive sounds.

Development in the Eighth Month

• Skin appears pink, smooth, congested, and edematous.

• Acceleration in surfactant production occurs.

• Lanugo begins to shed.

Development in the Ninth Month

• Hair grows longer with isolated lanugo on trunk and face.

• Umbilical cord is higher.

• Areolas are visible but lightly pigmented.

Fetal Development: Months 7 to 9 Continued

Continuing from the previous discussion, this section elaborates on functional developments during months seven to nine of fetal growth.

Functional Changes in the Seventh Month

• Lungs and pulmonary vascularization allow gas exchange.

• Central nervous system regulates temperature and breathing.

• Premature birth survival possible with intensive care.

Final Stages of Fetal Development

This part delves into the final stages of fetal development during the eighth and ninth months of pregnancy, highlighting morphological and functional advancements.

Morphological Changes in the Eighth Month

• Pink, smooth skin with rounded contours on trunk and limbs.

• Lanugo shedding initiates; nails cover nail beds softly.

Functional Changes in the Ninth Month

• Coordination of sucking and swallowing reflexes.

• Surfactant enables acceptable respiratory function.

Full-Term Fetal Development

Discussing fetal development at full term (37th to 40th week), emphasizing morphological characteristics and functional capabilities.

Full-Term Morphological Features

• Weight between 3000g - 3500g; length around 48cm - 52cm.

• Testicles descend into scrotal sacs; visible nipple pigmentation.

Full-Term Functional Capabilities

• Adequate thermal regulation; coordinated respiratory movements.

Gestational Duration Calculation

Exploring methods for calculating gestational duration based on clinical practices versus embryology perspectives.

Gestational Duration Calculation Methods

1. Clinical Practice:

• Count from last menstrual period (~40 weeks or 280 days).

2. Embryology Perspective:

• Begin counting from fertilization (~38 weeks or 266 days).

Determining Probable Date of Delivery

Detailing how obstetricians estimate probable delivery dates using Naegele's rule based on last menstrual period calculation method.

Naegele's Rule for Delivery Date Estimation

• Subtract three months from last menstrual period date; add a year plus seven days for estimated due date calculation example provided for clarity.

Terminology Related to Birth Timing

Defining terms related to birth timing concerning preterm, term, post-term births, as well as abortions based on gestational age criteria.

Birth Timing Terminology

• Term: Birth between weeks 37 to 42; Preterm: Before week 37; Post-term: After week 42.