The amniotic sac begins forming about 12 days after conception - the blastocyst becomes an embryo with three separate layers that will become the baby, the umbilical cord and the amniotic sac. This corresponds with implantation and hCG beginning to rise.
At 7 weeks of gestation, the amniotic sac is typically about the size of a small grape, measuring approximately 2 to 3 centimeters in diameter. This sac contains amniotic fluid, which helps cushion and protect the developing embryo. As the pregnancy progresses, both the amniotic sac and the amount of fluid will increase significantly.
Barr body....[NovaNet]
The amniotic sac can typically be visualized on an ultrasound as early as 4-5 weeks of pregnancy. However, it may be more consistently seen around 5-6 weeks.
An internal sonogram can show pregnancy as soon as 4 weeks. There will likely show an amniotic sac which is the first to form during pregnancy. Within a week after that you can see the fetus start to form. The heartbeat will likely show around 8 weeks.
Amniocentesis can be done no earlier than the fourteenth week of pregnancy. Sufficient amniotic fluid has to be present to do an amniocentesis. Amnios can be done well after 15 weeks but you shouldn't have one before then.
Until 13 weeks after the last period.
4-5 weeks do not touch the baby until 10-12 weeks though
Embryo
On average, the normal volume of amniotic fluid at 37 weeks is about 1000 mL or 1 L (34 fl oz). While this volume can vary significantly from one pregnancy to another, during late pregnancy a volume of less than 400 mL (13.5 fl oz) is called oligohydramnios; more than 2000 mL (68 fl oz) is called polyhydramnios.
Yur "baby belly" will not appear until the first few weeks of pregnancy.(:
Amniocentesis is a procedure in which a small amount of amniotic fluid is extracted from the amniotic sac surrounding the fetus for testing. It is commonly used during pregnancy to detect genetic abnormalities, chromosomal disorders, and other potential health issues in the fetus. The procedure is typically done between 14 and 20 weeks of pregnancy.
You normally do not begin to dilate until you pass 32 weeks in your pregnancy. Some women do not dilate until they are full term.