Thanks for the photo, Jessica!
NOTE: If you haven't seen my first post in this series, I recommend that you read it before you begin here, it 'sets the stage'. :-)
To begin at the beginning we really should set forth some guidelines as to what this is all going to look like. First off, some terms! (might as well get what may seem awkward out of the way first!)
Zygote/Embryo/Fetus/Baby: All of these terms are used (in order of development) to refer to an unborn child, however I most often just say 'baby', as I do truly believe that even a zygote (fertilized egg, not yet implanted) is already a human being with a soul and a name known by God.
Uterus: The place where the baby grows inside the Mama for approximately 9 months before entering this side of the world. It is attached to fallopian tubes (also known as oviducts) down which eggs travel from the ovaries. The baby does not grow in one's stomach (I'll never eat again...) or any such thing, but sometimes I will refer to the Mama's 'tummy'. Really though, baby grows in the uterus.
Vagina: Let's get that word out there! :-) Remember that this is the canal through which a baby is born. It is truly a marvelous thing that God has made, I mean think about it. It stretches to let a BABY pass through! The superficial layer of tissue in the vagina is stratified squamous epithelium, so it's basically like our regular skin, except not keratinized (toughened...sort of). Fantastic stuff.
Cervix: Many people don't know what this is, so if you're one of them, this is your big day! The cervix is the opening between the uterus and the vagina, and is a sphincter (circular muscle) that is shut for most of our lives. Every month it dilates (opens) just a tiny, tiny bit to let out the blood and uterine lining (this is menstruation), and then is shut the rest of the time. During pregnancy, it is sealed with a special mucus plug, which is released shortly before the baby is born. During labour (or often beginning before labour), it shifts from pointing posteriorly (back) to pointing anteriorly (forward), and dilates from 0 cm to about 10 cm, to allow the baby to pass through. In fact, this opening of the cervix is the whole point of labour!
Dilation and Effacement: Dilation is the opening of the cervix from 0cm to 1cm to 2 cm, and so on. Effacement is the thinning of the cervix. As the uterine contractions happen during labour, the muscles (and there are LOTS of them!) basically 'tug' at the cervix, slowly opening and thinning it around the baby's head (or toes, bum, or bag of waters).
Placenta: This is the baby's life source during pregnancy. The placenta is attached to the uterine wall, and is actually an organ which takes nutrients from the mother and transfers them to the growing baby for their development. Blood does not pass between the mother and baby, only nutrients. A baby can have a different blood type than the mother, and therefore you wouldn't want to mix that blood. It is the nutrients that pass through. I will explain this in more detail later.
Umbilical cord: The umbilical cord is the baby's lifeline between the placenta and its body. This is basically how a baby in utero 'breathes', gaining life-giving oxygen in its blood by going through capillaries in the placenta, and getting oxygen from the Mum's blood. Mama is breathing for two! Remember, the baby's heart is pumping, but the pulmonary circuit (the circuit where the waste-filled blood is pumped to the lungs, waste is breathed out, and blood is re-oxygenated to return to the rest of the body) is basically 'off' until the baby is born.
Labour and Birth: Obviously we will be talking about this more, but basically, as mentioned above, labour is the process of opening the cervix to let the baby through and into this world. Labour and birth have three stages. Stage 1 is the labour, Stage 2 is the birth of the baby, and Stage 3 is the birth of the placenta.
We'll leave it there for now! I might do another terms post if I feel that things are getting too snaky. :-) Next time we'll take a look at fetal development, so as to lay a foundation for what birth is supposed to look like.
Looking forward to seeing you next time,