Antibiotics and Pregnancy

Antibiotics can be used during pregnancy, but only according strict indications, if there is a very urgent reason. This is the case, written in instruction: «If expected benefit exceeds risk to mother and fetus». In any case, it should be done only under strict medical supervision and usually in a hospital (pathologic pregnancy department).

During first trimester, most drugs can harm developing fetus, therefore, in this period it is better to avoid these substances. The second and third trimesters are more secure, but each drug has its own terms when it can not be used. These terms should be well known to your doctor.

Since many bacteria are resistant to an antibiotic before treatment it is better to undergo a test for their sensitivity. Test results will show, which bacteria caused the disease and which antibiotic works best for it.

If the test for sensitivity is impossible to undergo for some reason, the doctor prescribes broad-spectrum antibiotics, that is those that kill all possible microbes.

When Are Antibiotics during Pregnancy Essential?

The most frequent reasons to prescribe Canadian antibiotics to pregnant women:

  • pyelonephritis;
  • pneumonia, severe bronchitis, quinsy;
  • severe intestinal infections;
  • purulent wounds and extensive injuries, burns;
  • severe infectious complications such as sepsis, blood infection;
  • specific diseases caused by rare bacteria: mite-born borreliosis, brucellosis and others.

In all these cases, antibiotics use is justified and necessary to prevent even greater complications. That is, the benefit to mother is much higher than the risk to the fetus.

Possible Risks

The main risk is exposed not to the mother but to her baby. Many of them enter the fetal bloodstream through the placenta and can have adverse effects on the body, which is currently the most rapidly growing.

All antibiotics list during pregnancy can be divided into three groups:

  1. completely prohibited, due to proven toxic effects on fetus;
  2. allowed, proved the absence of adverse effects;
  3. effects on the fetus are unknown, so they may be used only when absolutely necessary.


Tetracycline, doxycycline – passes through the placenta, accumulate in bones and fetus dental germs, violating their mineralization. Toxic to the liver.

Fluoroquinolones (Ciprofloxacin, Cipro, Nolicin, Abaktal, etc.) – prohibited, there are no reliable safety studies in pregnant women. Disable fetus joints in studies on the animal.

Clarithromycin (Klacid, Fromilid, Klabax) – safety at pregnancy is unknown. There is evidence of toxic effects on the fetus in animals.

Midecamycin, roxithromycin – the same as clarithromycin.

Aminoglycosides (Kanamycin, Tobramycin, Streptomycin) – pass through the placenta, exposing the high risk of complications for fetus kidneys and inner ear, can cause deafness in newborn. Gentamicin belongs to the same group, but its use is permitted according to health reasons in strictly calculated dosages.

Furasidin (Furamag, Furaginum), nifuroxazide – prohibited in connection with potentially harmful effects, safety data at pregnant women are not available.

Chloramphenicol (Laevomycetin, Synthomycin) – prohibited. Fastly passes through the placenta in high concentrations. Inhibits fetal bone marrow and violates blood cells division, especially during later stages of pregnancy.

Dioxydine – often used in surgical practice for disinfecting wounds. Prohibited during pregnancy, as it was proved to have toxic and mutagenic effects on the fetus at animals.

Co-trimoxazole (Bactrim) – consists of two substances: sulfamethoxazole and trimethoprim, which pass through the placenta in high concentrations. Trimethoprim – active folic acid antagonist (antivitamin). It increases congenital malformations, heart abnormalities risk, slows down fetal growth.

Allowed in Extreme Cases

Azithromycin – used only when absolutely necessary, in such cases as chlamydial infection in pregnant women. Negative effects on fetus have not been identified.

Nitrofurantoin – can be applied only during the second trimester, during first and third – prohibited.

Metronidazole (Klion, Trichopol, Metrogyl, Flagyl) – prohibited during the first trimester, can cause fetus brain, limb and genitalia defects. During second and third trimester its administration is allowed in absence of safer alternatives.

Gentamicin – allowed only according to health reasons (sepsis, blood infection) in strictly calculated dosages. In excess doses, there is a risk of deafness.

Safe (Allowed during Pregnancy)

All of the following drugs can be used during pregnancy. However, you must remember that any antibiotic is a potent drug and should not be taken without doctor’s prescription. After completing assigned treatment course you must come to re-appointment.

Penicillin and its analogs (Amoxicillin, Amoxiclav, Ampicillin) – pass through the placenta, but adverse effects on the fetus are usually absent. During pregnancy – cleared through kidneys in the faster regimen.

Cephalosporins (Cefazoline, Cefalexin, Ceftriaxone, Cefuroxime, Cefixime, Cefoperazone, Cefotaxime, Ceftazidime, Cefepime) – used during pregnancy without restrictions. Pass through the placenta in low concentrations. Negative effects on fetus have not been identified.

Erythromycin and josamycin (Wilprafen) and spiramycin – allowed for use. Passes through the placenta in low concentrations. Does not cause violations in fetal development and congenital abnormalities.


Antibiotics and Conception

Often there arises such situation when a woman, not knowing that she was pregnant, was taking antibiotics. What to do in this case? Will it hurt the baby? If an antibiotic was of the safe group, it is likely not to hurt. Prohibited medications during pregnancy in early stages can lead to miscarriage or missed miscarriage.

Only one thing can be done in this situation – cancel antibiotic immediately, as soon as pregnancy became evident. Then you have to wait. If medicine had a bad effect on an embryo, miscarriage may occur. If it did not affect in any way, and embryo survived, it is likely to further develop without any deviations.

In order to check whether embryo development has stopped, you can undergo a blood test for HCG (what is it?), preferably two-three times. Several identical results or too low figures would indicate a missed miscarriage. Another criterion is vaginal ultrasound, but on stage less than 4 weeks, it is not informative.

Resorting to abortion just because of fear that a child will be born with some disabilities is not necessary. In case of harmful effects on early stages, an embryo is likely to die than develop improperly. Malformations occur when harmful factor acts at later stages during organs growth.

If pregnancy is only planned and desired, it is better to refuse not only antibiotics during this period but also any substance harmfully affecting the fetus.