Deep in your uterus your embryo is growing at a furious pace. At this point, he's about the size of a sesame seed, or peppercorn and looks more like a tiny tadpole than a human. He's now made up of three layers – the ectoderm, the mesoderm, and the endoderm – which will later form all of his organs and tissues.
The neural tube – from which your baby's brain, spinal cord, nerves, and backbone will sprout – is starting to develop in the top layer, called the ectoderm. This layer will also give rise to his skin, hair, nails, mammary and sweat glands, and tooth enamel.
His heart and circulatory system begin to form in the middle layer, or mesoderm. (This week, in fact, his tiny heart begins to divide into chambers and beat and pump blood.) The mesoderm will also form your baby's muscles, cartilage, bone, and subcutaneous (under the skin) tissue.
The third layer, or endoderm, will house his lungs, intestines, and early urinary system, as well as his thyroid, liver, and pancreas. In the meantime, the primitive placenta and umbilical cord, which deliver nourishment and oxygen to your baby, are already on the job.
Every Thursday is the beginning of a new week- at this point at least. We have an ultrasound scheduled for September 27th to get count of babies, size and dates. We will have a more solid due date at that point, although, we're pretty sure this due date is correct within a day or so, but weirder things have happened!
So welcome to five weeks! So far here are the symptoms:
- tender breasts
- exhaustion
- waves of nausea, but no vomiting
- quite moody- this is in part to quitting my celexa cold turkey. Not smart I know, but I refuse to take pretty much anything medication wise when I'm pregnant.
- pants already getting tight. (OMG!!!)
