Abortion Methods: Trimester 2

--Medical Methods

--Surgical Methods

Fetal Development: Trimester 1

Fetal Development: Trimester 3

Stages of Pregnancy and Fetal Development Introduction

Home

By the end of the first trimester, fetal organs are fully established and external features are recognizable. During the three months of the second trimester, the fetus becomes sturdier and continues the development of organs.

Month 4 (see figure)

External Features: At four months fetal skin is transparent enough for underlying blood vessels to be seen clearly. Fingernails are well established and toenails begin to form. Nostrils by this time are almost formed and eyes move from the lateral sides of the head to the ventral side. Soft and thin hairs, called lunugo hairs, begin to grow on the scalp.(3)

Organ Systems: Internally, a male fetus forms seminal vesicle and ovaries in the female fetus contain primordial follicles. Throughout the body, brown fat formation begins, as does hematopoiesis (blood cell formation) in the bone marrow. Liver functionality begins. In the brain, pyramidal tracts begin to form and tranverse grooves appear on the dorsal surface of the cerebellum.(3)

A fetus at this stage had enough autonomy to suck its thumb and is active enough for the mother to feel the fetal movements.(3) The time when a mother first feels the movement of the fetus is called "quickening."(4)

Month 5 (see figure)

External Features: At five months, sebaceous glands accumulated at the surface of the skin begin to deposit verniz caseosa, which serves as a protective coating for the epidermis. The lanugo hairs that began formation during the fourth month now cover most of the entire body. Eyelids and eyebrows develop and abdomen begins to fill out.(3)

Organ Systems: Internally, a five-month-old fetus has functional sebaceous glands and the pituitary gland is mature enough to release thyroid-stimulating hormone. Myelination of the spinal cord begins, and the testes in a male fetus begin descending.(3)

Month 6 (see figure)

External Features: By the sixth month and the end of the second trimester, fetal skin is now red and wrinkled and lanugo hairs have darkened.

Organ Systems: The spinal cord has reached the S1 level and pulmonary surfactant begins to be secreted. This surfactant is a mixture of phospholipids and proteins; it will eventually line the aveoli and lower the surface tension in mature, adult lungs, allowing gas exchange.(3)