By one year a baby would have developed preference for adults, toys, and books they are accustomed to. They may show preference to these people or items, and may not be interested in accepting someone or something else as a replacement.

By 18 months a baby should have developed the ability to walk alone, including standing up, balancing, and taking steps. Babies who cannot walk by 18 months should be evaluated by their physician.

Endometriosis occurs when tissue that normally grows in the uterus implants and grows in other locations. This extra tissue growth — and the surgical removal of it — can cause scarring, which may obstruct the tube and keep the egg and sperm from uniting.

Causes of implantation failure include  genetic defects, thin endometrium, embryonic defects and endometriosis.

If you get the birth control shot regularly (every 12 weeks) it prevents pregnancy but you should use latex or female condom to reduce the risk of sexually transmitted infections.

There are different types and sizes of IUD and they can work for between 5 and 10 years depending on the type.