1. If you meant Typhoid Fever in the 3rd month (first trimester) of pregnancy

• Blood culture is the primary diagnostic test - positive in 60-80% of patients, ideally drawn before starting antibiotics. This remains the gold standard in pregnancy too - Sleisenger and Fordtran's Gastrointestinal and Liver Disease, p. 686.
• Bone marrow and stool culture can supplement blood culture, especially if the patient has already received antibiotics - Park's Textbook of Preventive and Social Medicine.
• Widal test (serology for O and H agglutinins against S. typhi) is still widely used in resource-limited settings (e.g. Indian subcontinent) but is nonspecific and not recommended as a standalone diagnostic by CDC - Jawetz Melnick & Adelberg's Medical Microbiology; Bailey and Love's Short Practice of Surgery.
• Newer rapid tests (e.g. TUBEX IgM test) exist as alternatives to Widal.

• First-trimester typhoid is less commonly reported than second/third trimester disease, but case reports describe placental abruption and vertical transmission when it occurs early in gestation.
• Persistent high fever/hyperthermia early in gestation carries a theoretical risk for the fetus (neural tube concerns with sustained maternal hyperthermia, and risk of miscarriage/abortion), which is why prompt diagnosis and treatment matter more in the first trimester than later.
• Treatment consideration: chloramphenicol/fluoroquinolones used outside pregnancy have safety concerns in pregnancy; treatment is typically guided toward antibiotics considered safer in pregnancy (e.g. ceftriaxone or azithromycin), with drug choice individualized by trimester.

2. If you meant Thyroid disease/testing in pregnancy

• TSH reference ranges shift downward in pregnancy (both lower and upper limits fall), so non-pregnant TSH cutoffs will misclassify patients. ATA 2017 guidance: use population/trimester-specific reference intervals; if unavailable, lower the TSH reference range by about 0.4 mIU/L and the upper range by about 0.5 mIU/L.
• TSH can be misleading in the first trimester (suppressed due to hCG cross-reactivity with the TSH receptor) - free T4 gives a more accurate picture of thyroid status in early pregnancy - Tietz Textbook of Laboratory Medicine, p. 4569-4594.
• Immunoassays for free T3/T4 are less reliable in pregnancy due to rising thyroxine-binding globulin (TBG) and falling albumin; liquid chromatography-tandem mass spectrometry is more accurate but not routinely available.
• Universal vs. targeted screening for thyroid disease in pregnancy remains debated among societies (ATA, ACOG, Endocrine Society); targeted screening criteria include age, prior adverse pregnancy outcomes, autoimmune disease, TPO antibody positivity, goiter, obesity, and family/personal thyroid history.
• TPO/Tg antibodies are found in 10-20% of pregnant women and are linked to higher miscarriage/preterm delivery risk, though routine levothyroxine treatment for antibody-positive euthyroid women isn't currently recommended by major societies.

Typhoid Fever Treatment in Early Pregnancy (1st trimester / ~3rd month)

Preferred antibiotics in pregnancy

• Third-generation cephalosporins - ceftriaxone or cefixime are the treatment of choice in pregnancy, including the first trimester. They are effective against most susceptible strains and considered the safest class of the standard typhoid regimens for use in pregnant women - Tintinalli's Emergency Medicine; Dermatology 2-Volume Set 5e (notes ceftriaxone as first-line "in children and pregnant women").
• Ampicillin/amoxicillin has historically been used in pregnancy-associated typhoid, especially where the organism is susceptible (pre-dates widespread multidrug resistance) - case series data (PMID 7821835, PMID 6335838).
• Azithromycin is a reasonable alternative, particularly for uncomplicated disease or where fluoroquinolone/cephalosporin resistance is a concern, though resistance to it is now emerging in some regions (Pakistan, Bangladesh) - Harrison's Principles of Internal Medicine 22e.

Antibiotics to avoid or use cautiously in early pregnancy

• Fluoroquinolones (ciprofloxacin) - the usual first-line drug in non-pregnant adults - are generally avoided in pregnancy. A clinical series found that of the few pregnant patients given quinolones, most were in the first trimester and had a spontaneous abortion (association, not proven causation, but it reinforced avoidance) - IJID study (Sulaiman et al.).
• Chloramphenicol - historically the original typhoid drug - carries risk of maternal bone marrow suppression and neonatal "gray baby syndrome" if used near term; generally avoided in pregnancy, particularly in the third trimester - Sabiston Textbook of Surgery, p. 2089.
• Trimethoprim-sulfamethoxazole - avoid in the first trimester (folate antagonism, theoretical teratogenic risk) and near term (risk of neonatal kernicterus).

Supportive management alongside antibiotics

• Hydration, electrolyte correction, and antipyretics - paracetamol (acetaminophen) is preferred over NSAIDs in pregnancy.
• Close fetal and obstetric monitoring: pregnancy-associated typhoid carries a real risk of spontaneous abortion, preterm labor, and rarely vertical transmission or placental abruption, especially when the fever is prolonged or high-grade in the first trimester - case reports (PMID 39928006, PMID 27579063).
• Monitor for typhoid-specific complications (intestinal perforation, hepatitis, relapse) as in non-pregnant patients; treatment duration is usually 7-14 days depending on the agent and clinical response.
• If the strain is multidrug-resistant or extensively drug-resistant (XDR, as seen in some South Asian outbreaks), susceptibility testing should guide therapy, since azithromycin and carbapenems may be the only effective options.

Bottom line