Reference:
- Dr. RPS Maternal and Newborn Care: A Comprehensive Guide and Source Book for Teaching and Learning, 2nd Edition, ISBN 9789719822653, by Rosalinda Parado Salustiano (Ch. 4, 64–79)
- Lecturer (V)
| Age | G&D (RPS) | G&D (V) |
|---|---|---|
| 4 weeks | All systems in rudimentary form: beginning formation of eyes, nose, and GIT Partitioning of the primitive heart begins; heart chambers are formed; the heart beats (14 days); the heart is completely formed by the end of 6 weeks With arm and leg buds By the end of the 4th week after ovulation, the chorionic sac is 2 to 3 cm in diameters, and the embryo is about 4 to 5 mm in length | - Dizziness due to nervous system development of the fetus. For this, glucose is the foremost requirement. This results in the slight hypoglycemia of the mother that results in dizziness. - Fetal Heart Beat begins 16 days after conception. |
| 8 weeks | Head size is large in proportion to the body, neuromuscular development, and some movements. Rapid brain development External genitalia appear | - Sex Differentiation (6th week) - Fetal Heart Tone auscultation with a doppler, unheard with a stethoscope. - Placental development (not fully functional) |
| 12 weeks | Placenta fully formed Functioning kidneys develop, secrete urine Centers of ossification in most bones With sucking and swallowing Gender distinguishable FHT detected by ultrasound (10 to 12 weeks) Crown-rump fetal length is 6 to 7 cm. Uterus is palpable just above the symphysis pubis | - Placenta is fully functional - Renal system becomes functional. This is when the fetus begins to urinate in-utero. |
| 16 weeks | More human appearance Quickening felt by the multigravida Meconium in the bowels External genitalia are obvious; gender correctly determined by experienced observers by inspection of the external genitalia at 14 weeks (Cunningham et al., 2022) Scalp hair develops Formed eyes, nose, and ears FHT detected by fetoscope By the end of 16 weeks, crown-rump length is 12 cm, and fetal weight is 110 g | - Sex Differentiation is complete, but the external genitals remain small, which may lead to false determination. - Fetal Heart Tone auscultation with a fetoscope. - Lanugo: fine downy hair on the shoulder, nape, arms, etc. - Quickening: first fetal movement felt by multiparous women. - IgG transfer from mother to fetus |
| 20 weeks | Skin is less transparent With vernix caseosa and downy lanugo covering the entire body Quickening is stronger, felt by the primigravida FHT is audible using a stethoscope Bones are hardening Weight is more than 300 g | - The best period for sex determination through ultrasound. - Vernix caseosa appears: the cheese-like substance for lubrication during delivery. - Fetal Heart Tone auscultation with a stethoscope. - Quickening: first fetal movement felt by primiparous women. |
| 24 weeks | Weight is about 630 g Body is well-proportioned Skin is red and wrinkled; fat deposition begins Hearing established Eyebrows and eyelashes are recognizable Canalicular period of lung development. When born, some may breathe, but most will die because the terminal sacs required for gas exchange have not yet formed | - Surfactant Production for alveolar lubrication. - Hearing ability develops: the best time to start singing or talking to the fetus. |
| 28 weeks | Weight is 1,100 g. The crown-rump length is about 25 cm Viable; immature if born at this time; surfactant production begins Thin skin, red, covered with vernix caseosa Body less wrinkled With iron storage Nails appear The pupillary membrane has just disappeared from the eyes | - Bone Ossification: fetal bone development. Calcium demand increases. This results in leg cramps for the mother. Premature occurrence of leg cramps indicate inadequate calcium intake. (Vitamin D increases Calcium absorption; Vitamin C increases Iron absorption). |
| 32 weeks | Weight is 1,800 g. The crown-rump length is about 28 cm Subcutaneous fats begin to deposit; the skin is smooth and pink More reflexes (moro) are present With iron and calcium storage Good chance of survival if delivered at this stage | - Iron is transferred to the fetus. - Ultrasound at this period shows high presence of calcium in the base of the placenta. Calcium may be visualized (placental grading) due to the clumping of calcium with each other. - Lanugo disappears. |
| 36 weeks | Weight is 2,500 g. The crown-rump length is about 32 cm Lecithin/sphingomyelin (L/S) ratio is 2:1. Nails firm With a definite sleep/wake pattern More rotund body because of subcutaneous fat deposition Lanugo disappearing Excellence chance of survival with proper care; survival is the same as term | - Vernix caseosa disappears. |
| 40 weeks | Weight: approximately 3,400 g. Crown-rump length is 36 cm Full-term, fully developed, with good muscle tone and reflexes Little lanugo If male, testes in the scrotum The age at the time of EDC counts from first day of LMP With other characteristic features of the newborn |
This occurs in three stages of prenatal development: the germinal (first two weeks after conception); the embryonic (third through eighth week); and the fetal (ninth week until birth) stages. Cell division begins approximately 24 to 36 hours after conception.
- Germinal Stage: from fertilization to two weeks; the period of pre-differentiation of organs. When the ovum is exposed to a teratogen, the “all or none” law applies, meaning the ovum is either damaged and becomes aborted, or is not damaged and continues normally.
- Embryonic Stage: from two weeks to eight weeks; the period of organ differentiation (organogenesis). It is the most dangerous period, as the introduction of a teratogen during this period may result in severe organ malformation and dysfunction.
- Fetal Stage: from eight weeks to birth; the period of post-differentiation for organs. When exposed to a teratogen, a malformation is least likely to occur. Even if the fetus is affected, the effects will most likely be an alteration in size or function but not in form.