The document discusses the development of an embryo from conception through the first trimester of pregnancy. It notes that an embryo becomes known as a fetus after the first three months. A placenta forms, allowing the fetus to receive nutrients and oxygen from the mother while removing waste. Key developmental milestones are outlined, such as the appearance of the neural tube, somites, and early structures of the heart and other organs. Childbirth consists of three phases: dilation of the cervix, delivery of the baby, and delivery of the placenta. A C-section may be performed if normal vaginal birth poses risks.

2.  Fetus – The name given to the embryo after the first
three months of gestation
 The embryo develops inside the cavity surrounded by
a membrane called amnion.
 Placenta – an organ made up of cells from the embryo
and the mother
◦ Allows the embryo to receive nutrients and oxygen and
removes carbon dioxide and other waste
◦ Acts as a defense barrier
◦ Secretes the hormones responsible for fetal development and
controls the changes in the mother’s body

3.  The trophoblast secretes enzymes that erode the uterine
walls and make the implantation of the embryo easier

4.  The embryo buries itself into the vascular layer of the
uterus and the placenta starts to develop
 The placenta receives substances from the mother and
removes the embryo’s waste.
◦ It also acts as a filter for the substances that are not meant to
reach the embryo.
 However, some small molecules (drugs, tobacco, toxins, alcohol,
certain medicines, and viruses) may still reach the fetus

5.  The embryo’s cells start to specialize
 On day 16, the neural tube (precursor to the central
nervous system) appears
 One of the most important processes in this phase is
cellular migration – cells change their position inside
the embryo
 From day 19, the somites (precursors to the spine)
develop
 Around day 20, the structure of the future heart
appears; it starts beating around day 25

6.  The connection between the embryo and the placenta
now takes place through a tube (later known as the
umbilical cord)
 Between day 25 and 40, the brain begins to develop
and the face, ears and neck are visible
 The precursors to the digestive organs, lungs, and
kidneys start to appear

7.  From day 61, the embryo becomes a fetus
◦ Almost all parts of the future individual are present
 At week 28, the fetus measures around 35 cm and
weighs more than a kilogram.
 Inside its brain, folds are forming, which make it
possible to increase the area of the brain within the
same volume (which is key to intellectual
development)

8. 8 weeks 12 weeks

9. 32 weeks

10.  Childbirth consists of three phases:
◦ Phase 1: Also called dilation phase, because uterine
contractions widen the neck of the uterus
 The amnion breaks and releases the amniotic fluid
◦ Phase 2
 Uterine contractions before stronger, longer and more frequent.
 The mother also contracts her abdominal muscles.
 Between these two forces, the baby is pushed out of the womb
 Once the baby is born, its umbilical cord is clamped and its
general state of health is checked
◦ Phase 3
 The last contractions of the uterus push the placenta out of the
mother’s body (about 15 minutes after the baby is born)

11.  A Caesarean, or C-section, is a surgical operation in
which the baby is taken out of the mother’s body by
means of an incision
 This is done when the baby is unable to be born in the
normal way, whether this is due to the health of either
the mother or the baby