Normal Pregnancy from Fertilization to Labor Flashcards
Describe the main events of fertilization
Fertilization between a haploid sperm and a haploid ova occurs in the ampulla of the fallopian tubes most commonly and is marked by:-completion of meiosis II by the ova-fusion of the nuclei to produce a diploid embryo-thickening of the zona pellucida to make it impenetrable
What happens to the embryo after fertilization on day 0?
There are rapid mitotic divisions that produce a 4 cell embryo by 24 hrs, an 8 cell embryo by 72 hrs, and a morula by 4 days,which enters the uterus and cavitates to producea blastocyst by 5 days
Describe the composition of a blastocyst
Once the morula cavitates to the form the blastocyst, an inner mass cell appears (to be the fetus), surrounded by an outer layer of trophoblast cells (destined to be the placenta)
When does implantation occur?
Probably day 8-9 from fertilization (although the embryo actually enters the uterus as a morula around days 5-6 and bounces around until it finds the right spot)
What is decidualization?
This is the process of progesterone from the corpus luteum preparing the endometrium for implantation by making it nutrient (glycogen and lipid) rich
How does implantation occur?
Trophoblastic cells invade the decidua. An important note to make is that the endometrium will actually re-develop around the entire embryo after it has invaded so that it can supply the entire structure with nutrients
When does hCG begin to be produced by trophoblastic cells?
only AFTER implantation (when this happens, a pregnancy can be detected via hCG levels on a BLOOD (not urine yet) test)
Normal gestation is calculated from when?
the first day of the last menstrual period (LMP)- b/c its easier to establish than the date of conceptionNOTE: this assumes a 28 day cycle no matter what actuality is
What is EDD?
Estimated date of delivery of estimated ‘due date’NOTE: Never confine a women to bedrest near the end of pregnancy (as was the old practice) due to risk of TE
What is a normal gestation?
40 +- 2 weeks (from the first day of the last menstrual period) or ‘40 weeks gestational age’
How is EDD calculated?
EDD is calculated by counting back 3 months from LMP and adding 7 daysEx: First day of LMP is May 10. EDD is February 17
What is the timeframe of the trimesters of pregnancy?
First: 0-14 weeksSecond: 14-28 weeksThird: 28-40 weeks
What is a ‘fetus’?
This is the term for a developing child during gestation, regardless of gestational age
When does organogenesis occur?
2-8 weeks gestation (fromfertilization)
What is abortion defined as?
The loss of pregnancy less than 20 weeks or less than 500 gm
What fetuses have a chance of viability?
anything 23+ weeks ofgestation. You would not put a pt. through a C-section if less than 23 weeks
What is preterm? Late term? Postterm?
Preterm- less than 37 weeksLate term- 41+ weeks gestationPostterm- 42+ weeks gestation (associated with AEs if they arent born soon during this period)
What is a gravid pt? Parity?
A gravid pt. is currently pregnant before while a parity pt. has had a baby before (can be either dead OR alive at birth)
Describe a G3P1011 pt.
Pregnant now (has been pregnant 3 times), one term birth, no preterm births, one abortion (could be spontanoeus OR induced), and one living child
What are some indications that pregnancy may be occurring?
Missed menses, followed by morning nausea and vomiting (typically worse in the first trimester), breast tenderness