Table 2. A summary of confounders included in all cohort studies.

AP - acetaminophen; BSID - Bayley Scales of Infant Development; MSCA - McCarthy Scales of Children's Abilities; IQ - intelligence quotient; UTI - urinary tract infection; NSAIDs - non-steroidal anti-inflammatory drugs; ADHD - attention-deficit/hyperactivity disorder; BMI - body mass index; NCE - negative control exposure

Study author	Confounders/covariates Included and adjusted in the study
Avella-Garcia et al. [21].	1. Analgesia, 2. infection, 3. others. The region, child's gender, age at testing, performing psychologist determining the test quality (only for BSID and MSCA), maternal social class, gestational age at birth, maternal IQ, education, chronic illness in mother, fever, or UTI not related to AP use during pregnancy.
Bornehag et al. [19].	Maternal weight, education, smoking, week of enrollment and child's sex.
Liew et al. [26]. (studying child's IQ)	Maternal fever during the pregnancy, infection/inflammation, diseases affecting muscles and joints, child's sex, mother's age at childbirth, parity, parental education index, maternal IQ, smoking and alcohol use during pregnancy, use of NSAIDs during pregnancy.
Ystorm et al. [25].	Parental symptoms of ADHD (measured through self-screening), maternal self-reported smoking and alcohol use during pregnancy, maternal symptoms of anxiety and depression measured at 18- and 30-week gestation, maternal education, age, marital status, BMI at 18-week, parity, birth year centered to 1999.
Vlenterie et al. [20].	Each medical condition and respective medication use during the pregnancy were assessed. Illnesses like pain, fever, and infections were included in the questionnaires. Maternal age at delivery, pre-pregnancy BMI, parity, marital status or cohabiting, education, smoking, alcohol and folic acid use during pregnancy, maternal depression symptoms assessed through The Hopkins Symptoms Checklist, The SCL-5, infections, fever, headache/migraines, pelvic girdle pain, back/neck/abdominal pain, medications (NSAIDs, antiepileptics, antidepressants, opioids, triptans, and benzodiazepines) use during pregnancy.
Gervin et al. [28].	Infant's sex, gestational age at delivery, maternal age, smoking, and alcohol use during pregnancy.
Tovo-Rodrigues et al. [18].	Child's sex, mother's education, age, skin color, parity, smoking and alcohol use during pregnancy, mood issues, infection, pre-pregnancy BMI, NSAIDs use.
Liew et al. [22]. (attention and executive function)	Mother's age at childbirth, parity, parental education index, maternal IQ, maternal anxiety and depression, pre-pregnancy BMI, smoking, and alcohol during pregnancy, use of aspirin or ibuprofen, child's sex, indications of acetaminophen use: 1. fever, 2. infection/inflammation, 3. pain or musculoskeletal disease, 4. mothers who did not experience these symptoms during the pregnancy. Some confounders were adjusted but not included in the final analysis because of minimal effect. These are paternal age, prenatal use of antidepressants, folic acid intake, maternal marital status at the time of interviews.
Arneja et al. [24].	Maternal age, ethnicity, BMI at baseline, education, smoking in three months before pregnancy, fever during pregnancy, paternal smoking in three months before pregnancy, comorbidities (comorbidity index was created), use of other pain relievers like NSAIDs, diclofenac, morphine, oxycodone, and codeine.
Parker et al. [23].	1. Upper respiratory tract infections, 2. headaches, 3. fever, 4. pain/injury maternal age, race, education, marital status, parity/gravidity, smoking and alcohol during pregnancy, paternal age at delivery, pre-pregnancy BMI, infant's sex, medication use for depression and anxiety, other indications of AP use.
Liew et al. [29]. (NCE analysis)	Maternal age at the child's birth, child's birth order, child's birth year, maternal diabetes during the pregnancy, preeclampsia, use of aspirin alone or in combination, other NSAIDs use, AP used in negative control periods (four years before and after the pregnancy), child's sex. Indications of AP use, such as depression, rheumatoid arthritis, and migraine headaches, were included and adjusted. Maternal social factors like income, education of the partner. Lifestyle factors like maternal smoking and alcohol use during the pregnancy.
Ji et al. [17].	Maternal age at delivery, maternal race/ethnicity, mother’s marital status and education level, maternal smoking and alcohol use before or during the pregnancy, history of stress during the pregnancy, maternal BMI, history of breastfeeding, parity, ever use of illicit drugs and maternal fever during the pregnancy. In addition, lead levels in early childhood, sex of the child, birth weight, preterm birth and the delivery type were recorded. Diagnoses of ADHD, anxiety or depression, intrauterine infection, or inflammation in the mother were also included and adjusted. Data for these confounders were collected from questionnaire interviews with mothers by trained research staff and electronic medical records.