,Fertilization occurs when a sperm attaches to the outer protein layer
of the egg.
The attached sperm releases enzymes that allow the sperm to fully
penetrate the zona pellucida and contact the egg’s cell membrane.
The membranes of the sperm and egg then combine to create a
new, single cell called a zygote
Fertilization usually occurs in the fallopian tube. The fertilized
egg travels down the fallopian tube over 2 days, with cell
division taking place. By day 3, the fertilized egg reaches the
uterus. Cell division continues for another 2 to 3 days in the
uterine cavity before implantation
Approximately 6 days after fertilization, the cell mass is
termed a blastocyst. Human chorionic gonadotropin (hCG)
now is produced in amounts detectable by commercial
laboratories
,By day 10 postfertilization, the blastocyst is implanted under the
endometrial surface and receives nutrition from maternal blood. On
the first day of the third week postfertilization its called embryo .
After the embryonic period (between weeks 2 and 8 postfertilization),
the embryo is renamed a fetus. Most body structures are formed
during the embryonic period, and they continue to grow and mature
during the fetal period. The fetal period continues until the pregnancy
reaches term, approximately 40 weeks after the last menstrual
period.
Gestational age refers to the age of the embryo or fetus beginning
with the first day of the last menstrual period, which is about 2
weeks prior to fertilization
Early symptoms of pregnancy include fatigue and increased frequency
of urination. After the first or second missed menstrual period, nausea
and vomiting can occur. usually resolve at 14 to 16 weeks of gestation
, Signs of pregnancy include cessation of menses, change in cervical
mucus consistency, bluish discoloration of the vaginal mucosa,
increased skin pigmentation, and anatomic breast changes
PK changes during pregnancy:
Physiologic changes begin in the first trimester and peak during
the second trimester
During pregnancy, maternal plasma volume, cardiac output, and
glomerular filtration increase by 30% to 50% or higher, potentially
lowering the concentration of renally cleared drugs.
As body fat increases during pregnancy, the volume of distribution
of fat-soluble drugs may increase
Plasma albumin concentration decreases, which increases the
volume of distribution of drugs that are highly protein bound
Hepatic perfusion increases, which could theoretically increase the
hepatic extraction of drugs
of the egg.
The attached sperm releases enzymes that allow the sperm to fully
penetrate the zona pellucida and contact the egg’s cell membrane.
The membranes of the sperm and egg then combine to create a
new, single cell called a zygote
Fertilization usually occurs in the fallopian tube. The fertilized
egg travels down the fallopian tube over 2 days, with cell
division taking place. By day 3, the fertilized egg reaches the
uterus. Cell division continues for another 2 to 3 days in the
uterine cavity before implantation
Approximately 6 days after fertilization, the cell mass is
termed a blastocyst. Human chorionic gonadotropin (hCG)
now is produced in amounts detectable by commercial
laboratories
,By day 10 postfertilization, the blastocyst is implanted under the
endometrial surface and receives nutrition from maternal blood. On
the first day of the third week postfertilization its called embryo .
After the embryonic period (between weeks 2 and 8 postfertilization),
the embryo is renamed a fetus. Most body structures are formed
during the embryonic period, and they continue to grow and mature
during the fetal period. The fetal period continues until the pregnancy
reaches term, approximately 40 weeks after the last menstrual
period.
Gestational age refers to the age of the embryo or fetus beginning
with the first day of the last menstrual period, which is about 2
weeks prior to fertilization
Early symptoms of pregnancy include fatigue and increased frequency
of urination. After the first or second missed menstrual period, nausea
and vomiting can occur. usually resolve at 14 to 16 weeks of gestation
, Signs of pregnancy include cessation of menses, change in cervical
mucus consistency, bluish discoloration of the vaginal mucosa,
increased skin pigmentation, and anatomic breast changes
PK changes during pregnancy:
Physiologic changes begin in the first trimester and peak during
the second trimester
During pregnancy, maternal plasma volume, cardiac output, and
glomerular filtration increase by 30% to 50% or higher, potentially
lowering the concentration of renally cleared drugs.
As body fat increases during pregnancy, the volume of distribution
of fat-soluble drugs may increase
Plasma albumin concentration decreases, which increases the
volume of distribution of drugs that are highly protein bound
Hepatic perfusion increases, which could theoretically increase the
hepatic extraction of drugs
