You asked

Do STDs affect my pregnancy? How can they affect my baby?

Not many people like to talk about sexually transmitted diseases (STDs), but it is important to be open about all health issues with your doctor to ensure that you have a safe and healthy pregnancy and deliver a healthy baby. You should have been tested at your gynaecological examination annually. If this hasn't been the case, and you haven't been tested recently, it’s imperative that you be tested and treated for any STDs, especially if you are pregnant. Take all recommended treatments (if they are not detrimental to the baby's health) and frequently ask your doctor questions.

Here are some must know facts about STDs and how they may affect your baby:

Chlamydia and Gonorrhoea:
You are risking having your water breaking early, a pre-term birth, a miscarriage, the baby contracting pneumonia or an eye infection (due to contact during delivery) if you have either of these diseases. Fortunately, you can be treated during pregnancy with antibiotics. Remember, most women have no symptoms, so it's always a good idea to be tested just in case you have them.
A sign of herpes is painful sores or blisters in your private areas, but sometimes there are no tell tale symptoms at all. The sores will heal and then reappear randomly since the virus remains in your body. If there is an outbreak near the time of delivery, your doctor may recommend the safer option of a C-section delivery; otherwise the baby may be infected (this can cause blindness, mental retardation, damage to the nervous system and even death). A C-section is not 100 percent effective in preventing these possible outcomes for your baby if your water breaks a few hours before birth, as the virus can still spread to the baby. 
Human Papillomavirus (HPV):
This usually results in itchy, bloody genital warts, but not always.  The good news is that there is only a small chance that the baby can be infected (in some rare cases, the baby gets warts on their throat). The genital warts usually disappear by themselves and certain medications may cause birth defects and should not be used during pregnancy. A C-section may become necessary if the warts make it difficult for the baby to travel down the birth canal.
Syphilis can be difficult to detect since the painless sore (a chancre) can hide deep within your vagina. Blood tests done in the early stages or a sample from the sore will determine if you do have Syphilis. It can be passed to the baby through the bloodstream and may cause a miscarriage, stillbirth, or your water to break early. If the baby gets syphilis, they may develop birth defects, but treatment after birth can prevent further damage. If you do have syphilis, it’s important you take care of yourself (and the baby) and get treated within the first three to four months of pregnancy.
There may be no symptoms. But there is a risk for your water to break early and for pre-term delivery. The good news is that it is treatable with antibiotics during pregnancy.
Human Immunodeficiency Virus Infection (HIV):
HIV can be passed to the baby during pregnancy or delivery. Without treatment, there is a 25% chance that the baby will get the virus. Treatment should continue through pregnancy to the delivery and be given to the baby for their first six weeks.  A C-section may help prevent spreading the virus, but nursing can pass the virus to the baby, so should be avoided.
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More questions

The best timing for pregnancy testing is once you miss your period.
Ectopic pregnancies are fertilized eggs which implant themselves outside of the uterus. They must be terminated and can indicate future fertility issues.
Ovulation is the period during which you can conceive. Tracking ovulation can be tricky, but you can increase your chances of conceiving through math, prediction kits, or simple scientific observation.
Implantation bleeding is not a common experience, but some women do report small amounts of blood with or without cramping roughly a week or less before their anticipated period.
Pregnancy tests are only as good as the execution. Read all instructions to avoid getting inaccurate results on a home pregnancy test.
The best over the counter kits measure luteinizing hormone (LH).
There are many things that you can do to increase your chances of getting pregnant.
How STD’s can affect your pregnancy, your baby and how you should deal with them during pregnancy.
Taking care of your body before and during pregnancy
Ovulation occurs just about two weeks after the first day of your period.