At 12 weeks, all your baby's major organs are all in place and from now on will just keep growing larger. The area on the skull that is commonly referred to as the "soft spot" (fontanel) on a newborn is very large at this point, allowing for a great deal of brain growth. The baby's profile is well formed, with a distinctive nose and chin. External genitals are beginning to be recognizable as male or female.
She is extremely busy at 12 weeks. Not only is she growing at an amazing rate -- she has almost doubled in size in the last three weeks alone -- but she is moving and stretching about in her warm amniotic bath. She is still too small for you to feel her moving, but if a heartbeat hasn't been detectable at your earlier prenatal visits, you might be able to hear it this week. Her hair and nails are continuing to grow, and her bones are growing firmer. Her digestive system is becoming more complex and efficient and is now able to absorb some basic nutrients.
As your pregnancy progresses and you enter your second trimester, your morning sickness should ease. When you begin to feel better, you'll probably start making plans for life after childbirth. Perhaps you're fixing up a room for the baby, beginning to borrow or purchase equipment like a crib, car seat, and high chair, as well as infant clothes. You and your partner are probably starting to jot down baby names and to discuss issues like parental leave and childcare.
But as the two of you look ahead to life as new parents, don't neglect your own relationship. Like any other major life change, having a child can put strain on a marriage. Take time now, before your twosome becomes a threesome, to nurture your partnership. Remember, there are still many months to go before your baby arrives. Try to plan a vacation together or at least some special weekends. Talk about your fears, and encourage your partner to discuss his own. It is likely that, as excited as you are, you both have some apprehensions.
If you already have other children, take time to nurture these bonds as well. You can prepare your toddler for a new sibling by reading age-appropriate books on the subject. Some hospitals offer regular workshops for older siblings to help children talk and work through their concerns about becoming a big brother or sister. Consider taking a family trip before the baby comes.
Without being heavy-handed, encourage your child to talk about her worries and feelings, and do all you can to comfort her -- while acknowledging that a big change is coming to all of your lives. Don't dismiss or minimize her concerns, or pressure her to act happy if she is not. She is likely to be ambivalent about having a new brother or sister -- even downright furious. She will appreciate it if you are honest and direct. You and your partner can reassure your child -- by your actions as much as your words -- that she is not going to be supplanted by this new member of the family, and that there is plenty of love to go around.
Campbell, Stuart MD. Watch Me Grow! St. Martin's Press.
Curtis, Glade OB/GYN and Judith Schuler, MS. Your Pregnancy Week by Week , Da Capo Press.
Nemours Foundation. Week 12: Your Baby's Development. http://kidshealth.org/parent/pregnancy_calendar/week12.html