1. Assoc. prof. Edyta Mądry MD PhD Poznań University of Medical Sciences
Pregnancy
Assoc. prof. Edyta Mądry
MD PhD
Poznań University of Medical Sciences

2. PREGNANCY Edyta Mądry MD, PhD Department of Physiology
Medical University
Poznań

3. Pregnancy Definition The period from conception to birth.

4. Conception
Conception means a woman's egg has been fertilized by a man's sperm.
                                                                   

5. ⃰ Conception
A secondary oocyte can be fertilized for about 24 hours after ovulation
Sperm remain viable for up to 72 hours within the female reproductive tract

6. ⃰ Fertilization
Fertilization usually takes place in the outer one-third of the uterine tube (ampulla of oviduct), but can ocasionaly take place in the abdominal cavity cervics of uterus (ectopic pregnancy)
Sperm swim up the female reproductive tract, aided by muscular contractions of the uterus stimulated by prostaglandins in the semen.

8. How does it start?
Sperm reach ovum and cluster around it

9. Only one sperm is allowed to penetrate egg

10. ⃰ Gestation (+ or – 2 weeks)
Gestation in singleton pregnancies lasts an average of 40 weeks (280 days) from the first day of the last normalmenstrual period (LNMP).
Assumption:
Fertilized 14 days after the first day of LNMP
Gives birth 38 weeks after fertilization (+ or - 2 weeks)
10 lunar months = 9 calendar months = 280 days
(+ or – 2 weeks)

11. ⃰ How to calculate the time of birth Naegele's rule
1. Determine first day of LNMP
2. Add one year
3. Subtract three months
4. Add seven days
For example: first day of LNMP April 21st, 2015
Resulting data of estimated data of birth : January 28 , 2016
(+ or – 2 weeks )

12. Fertilization size: 0.1 - 0.15 mm 1 Oocyte 300 Million Sperm
24 hours post ovulation
size: mm

13. Fertilization When the sperm penetrates the egg,
the egg immediately releases a chemicals creating a hard “shell” around it to keep all other sperm out and prevent polyspermy

14. Fertilization FERTILIZED EGG = ZYGOTE
The fertilization process takes about 24 hours.
It takes about ten hours to navigate the female productive track, moving up the vaginal canal, through the cervix, and into the fallopian tube where fertilization begins.

15. Cleavage First Cell Division, Mitotic division size 0.1 - 0.2 mm
days post-ovulation

16. 2 cell zygote
The zygote begins to develop
4 cell zygote

17. Three to four days after fertilization.
morula (mulberry shaped)- about 16 cells
morula leaves the fallopian tube and enters the uterine cavity

18. 8 cell zygote
16 cell morula

19. Early Blastocyst Two cell types are forming:
When zygote divides to 32 cells
it becomes known as a blastocyst
size mm
4 days post-ovulation
blastocyst formation
Two cell types are forming:
embryoblast (inner cell mass on the inside of the blastocele)
trophoblast (the cells on the outside of the blastocele).

20. Implantation Begins Human Chorionic Gonadotropin (hCG) level risemm
5 - 6 days post-ovulation
The trophoblast cells secretes an enzyme which erodes the epithelial uterine lining and creates an implantation site for the blastocyst (see slide number 22)

21. The blastocyst embeds into the uterine lining,

22. Implantation ovary continues producing progesterone
trophoblast cells continue releasing human chorionic gonadotropin (hCG)
Endometrial glands in the uterus enlarge in response to the blastocyst and the implantation site becomes swollen with new capillaries ( see slaids 26 and 27).

23. Implantation

24. Implantation Completed
Placental Circulation System Begins to form mm
days post-ovulation
Trophoblast cells engulf and destroy cells of the uterine lining creating blood pools, both stimulating new capillaries to grow and foretelling the growth of the placenta.

25. Implantation Completed
The inner cell mass divides, rapidly forming a two-layered disc
The top layer of cells will become the embryo and amniotic cavity
The lower cells will become the yolk sac.

26. yolk sac amniotic cavity ⃰ Inner cell mass forms two cavities:
⃰ In humans the yolk sac produces blood cells and future sex cells
The amniotic cavity becomes the cavity in which the embryo floats.
Fluid is produced from fetal urine, and secretions from the skin, respiratory tract, and amniotic membranes.

28. Symptoms of early pregnancy
Food cravings or aversions
Smell sensitivity
Heartburn
Missed Period
Morning Sickness
Constipation
Mood Swings/ Irritability
Higher body temperature
Low Back Pain
Tender breast
Bloating / Weight Gain
Fatigue

29. Four Weeks
After the cluster of cells attaches to the womb it is called an embryo. .

30. Day 24
Day 22

31. Day 26
Day 28

32. At the end of 4 weeks: Embryo is 1/4 inch in length
Heart, digestive system, backbone and spinal cord begin to form
Placenta (sometimes called "afterbirth") begins developing

33. At the end of 8 weeks: Embryo is 1 1/8 inches in length
Eyes, nose, lips, tongue, ears and teeth are forming
Penis begins to appear in boys
Embryo is moving, although the mother can not yet feel movement

34. At the end of 12 weeks: Fetus is 2 1/2 to 3 inches long
Weight is about 1/2 to 1 ounce
Nails start to develop and
earlobes are formed
Arms, hands, fingers, legs, feet and toes are fully formed
Eyes are almost fully developed
By this stage, a fetus has developed most of his/her organs and tissues
                                                                     

35. Fetus is developing reflexes such as sucking and swallowing.
At the end of 4 months:
Fetus is 6 1/2 to 7 inches long
Weight is about 6 to 7 ounces
Fetus is developing reflexes such
as sucking and swallowing.
Fingers and toes are well defined
Sex is identifiable

36. At the end of 5 months: Mother begins to feel fetal movement
Fetus is 8 to 10 inches long
Weight is about 1 pound
Hair begins to grow on his/her
head
Soft woolly hair called lanugo
covers fetus body
Mother begins to feel fetal movement

37. Weight is about 1 3/4 to 2 pounds
At the end of 6 months:
Fetus is 11 to 14 inches long
Weight is about 1 3/4 to 2 pounds
Eyelids begin to part and eyes open occasionally for short periods of time
Fetus is able to hiccup

38. At the end of 7 months: Fetus is 14 to 16 inches long
Weight is about 2 1/2 to 3 1/2
Pounds
Fat layers are forming
If born at this time, he/she will be
considered a premature baby
and require special care

39. At the end of 8 months:
Fetus is 16 1/2 to 18 inches long
Weight is about 4 to 6 pounds
Overall growth is rapid this month
Tremendous brain growth occurs
Most body organs are now developed with the exception of the lungs
Movements or "kicks" are strong enough to be visible from the outside

40. At the end of 9 months:
Fetus is 19 to 20 inches long
Weight is about 7 to 7 ½
pounds
The lungs are mature
Baby is now fully developed and can survive outside the mother's body
He/she settles down lower in the abdomen in preparation for birth and may seem less active

41. Labor (parturition)- Stage one
the period from the onset of true labor contractions until the cervix is completely dilated at 10 cm.
The uterine contractions cause the cervix to dilate, and the amniotic sac may rupture.
Usually lasts 6 – 24 hours depending on the number of previous deliveries.

44. Stage 2 Period from maximal cervical dilation until
the birth of the baby
Lasts minutes to
an hour
Contractions become
more intense and frequent.

45. Stage 3 The expulsion of the placenta
Usually occurs within 15 minutes after the birth of the baby, but can range from 5 to 60 minutes.

47. ⃰ Placenta 10-12 weeks is the period of placenta formation
Trophoblast cells use same molecular mechanisms as tumors, but are highly regulated and controlled

48. Placenta FETAL SIDE MATERNAL SIDE They provide… protection nutrition
respiration
excretion
hormone production

49. ⃰ Functions of Placenta
Exchange of gases between fetus and mother
Delivery of nutrients from mother to fetus
Delivery of antibodies from mother to fetus
Removal of fetus waste
Secretion of hormons including human chorionic gonadotropin ( hCG), progesterone, estrogen, and human chorinic somatotropin (hCS)

50. Placental barrier
Maternal and fetal blood do not mix- “placental barrier”

51. Metabolic Functions of the Placenta
Glycogen synthesis and storage
Cholesterol synthesis: placental cholesterol is precursor for placental progesterone and estrogens
Protein production

52. ⃰ Endocrine Functions Placenta Produces Peptide hormones
Human Chorionic gonodotrophin (hCG) - secreted early and helps to maintain synthesis of progesterone
Human placental lactogen (hPL): increase supply of glucose to future by decreasing maternal stores of fatty acids by altering maternal secretion of insulin
Insulin-like growth factors (IGF): IGF signaling system is a major regulator of growth in fetus and infant

53. ⃰ Endocrine Functions Steroid hormones
Progesterone: produced by placenta, needed to maintain non-contractile uterus
Estrogen: produced by placenta drives many processes in pregnancy

54. How important are hormones ?
An XY individual with androgen insensitivity syndrome.
Despite the XY karyotype and the presence of testes, such individuals develop female secondary sex characteristics.
Internally, however, these women lack the Müllerian duct derivatives and have undescended testes. (Photograph courtesy of C. B. Hammond.)

55. Sex differentiation

56. ⃰ Female development
The ovary makes thecal cells and granulosa cells, which together are capable of synthesizing estrogen.
Under the influence of estrogen (first from the mother, then from the fetal gonads), the
Müllerian duct differentiates into the female genitalia.

57. ⃰ 3 hormones necessary for male development
1. Müllerian Inhibiting Substance (MIS) = anti-Müllerian duct factor (AMH), causes the Müllerian duct to regress.
2.Testosterone, causes the differentiation of the Wolffian duct into the male internal genitalia.
In the urogenital region, testosterone is converted into
3. Dihydrotestosterone (DHT), that causes the morphogenesis of the external genitali (penis) and prostate gland.

58. ⃰ In green organs form under the influence of Dihydrotestosterone

59. ⃰ Hormones in pregnancy

60. ⃰ Function of Human Chorionic Gonadotropin
Prevent degeneration of the corpus luteum
Stimulates the corpus luteum to secrete estrogen and progesteron
Stimulates steroid synthesis in the developing fetal adrenals
Stimulates fetal gonads, especially testosteron production by the fetal testes.
Suppresses maternal lymphocytes and reduces the possibility of immunoreactions against the fetus.

61. ⃰ What does progesterone do?
It maintains the lining of the uterus which makes it possible
for a fertilized egg to attach and survive
Makes cervical mucous accessible by sperm
Prevents immune rejection of the developing baby
Increases libido around ovulation
Protects against endometrial, breast, ovarian and prostrate cancer
Normalizes blood clotting
Increase body temperature

62. Please note!
⃰ The information marked with a red star are the most important in the process of preparing up for the final exam.