29_Pregnancy Flashcards
How is dated pregnancy?
1st day after the last period (menstrual cycle)
What are the 3 important phases of pregnancy and what name is given to the baby in development?
Week 1 to 2 - zygote and blastocyst.
Week 3 to 8 - embryo
Week 9 to 38 - fetus
What is the most critical period during the pregnancy for the baby?
Between week 3 and 8
Zygote
Diploid cell (2 copies of genetic material) resulting from the fusion of 2 haploid gametes (ovule and spermatozoid). He is formed in the fallopian tube.
Blastocyst
Structure formed in the early stage of development. It possesses an inner cell mass which subsequently forms the embryo. The outer layer consists of cells collectively called the trophoblast. The trophoblast gives rise to the placenta.
The blastocyst travels through the fallopian tube into the uterus and it’s implantation in the uterus endometrium occurs about 5 days after fertilization:
Consequences of an exposure to a potential toxic agent during the development phases
Week 1 to 2: all or non phenomenon => no effect or pregnancy termination.
Week 3 to 8: placenta fully functional and organogenesis occurs => embryo highly susceptible to toxic agent with major congenital abnormalities (cardiac, spina bifida, limb defects)
Organs are all completely formed at the end of the ninth week except CNS.
Week 9 to 38 = fetal period - development = primary functional and growth. Exposure could cause minor congenital abnormalities and functional defects.
What is the role of the placenta during pregnancy?
The placenta is the functional unit between the fetal and the maternal blood supply. There is no mixing of the two systems, but exchange of nutrients, oxygen, and waste products occurs primarily via passive diffusion (gradient concentration). Few substances are actively transported (eg amino acids).
Drug-related factors affecting the drug transfert between the mother and the fetus during pregnancy?
Molecular weight Drug pKa Lipid solubility of the drug Volume of distribution of the drug and plasma protein binding Drug half life
Other factors than the drug-related one that affect the drug transfert between the mother and the fetus?
- Placenta changes during pregnancy: becomes thinner and expands during pregnancy => decrease diffusion distance and increase surface area of exchange.
- Maternal PK changes during pregnancy:
- enhance blood flow through the kidneys => increase renal clearance of drugs.
- Activity of cytochrome systems is modified: CYP450 with increased activity during pregnancy (2D6, 2C9, 3A4) and CYP 450 with decreased activity (1A2, 2C9).
- 2 major drug-binding proteins (albumin and AGP) level decreases during pregnancy.
What are the FDA categories for drug during pregnancy?
Category A: could be use Category B: with caution Category C: do not use Category D: contraindicated Category X: strictly contraindicated
Teratogenic agents
Vitamin A derivatives, Warfarin, Androgenic agents, Ethanol, Antineoplastics, Anticonvulsivants, Infections, Cigarette smoking.
Drug category A
Adequate, well-controlled studies in pregnant women have not shown an increased risk of fetal abnormalities.
Category B drugs
Animal studies have revealed no evidence of arm for the fetus; however there are no adequate and well-controlled studies in pregnant women.
Or animal studies have shown an adverse effect, but adequate and well-controlled studies in pregnant women have failed to demonstrate a risk to the fetus.
Category C drugs
Animal studies have shown an adverse effect, and there are no adequate and well-controlled studies in pregnant women.
Or no animal studies have been conducted, and there are no adequate and well-controlled studies in pregnant women.
Category D drugs
Studies-, adequate, well-controlled, or observational- I’m pregnant women have demonstrate a risk to the fetus. However, the benefits of therapy may outweigh the potential risk.
