| PNA (days)a | Study | No. of infants | Feeds per day | SD |
|---|---|---|---|---|
| Exclusively breastfed term infants | ||||
| 1 | Yamauchi & Yamanouchi, 1990 | 140 | 4.3 | 2.5 |
| de Carvalho et al., 1982 | 46 | 6.7 | 2.8 | |
| Houston et al., 1983 | 18 | 4.7 | 1.2 | |
| 2 | Ferris et al., 1993; Neubauer et al., 1993 | 11 | 6.1 | 1.4 |
| Yamauchi & Yamanouchi, 1990 | 140 | 7.4 | 3.9 | |
| de Carvalho et al., 1982 | 46 | 8.7 | 3.1 | |
| Novotny & Mata, 1983 | 1 | 8 | NR | |
| Houston et al., 1983 | 18 | 5.8 | 1.2 | |
| 3 | Ferris et al., 1993; Neubauer et al., 1993 | 11 | 7.8 | 1.9 |
| Jia et al., 2018 | 71 | 8.3 | 2.1 | |
| Houston et al., 1983 | 18 | 7 | 0.9 | |
| de Carvalho et al., 1982 | 46 | 9.2 | 2.7 | |
| 4 | Houston et al., 1983 | 18 | 7.1 | 0.9 |
| de Carvalho et al., 1982 | 46 | 9.5 | 3.3 | |
| 5 | Houston et al., 1983 | 18 | 7.3 | 1.4 |
| de Carvalho et al., 1982 | 46 | 9.3 | 2.7 | |
| 6 | de Carvalho et al., 1982 | 46 | 10.3 | 3.4 |
| 7 | Ferris et al., 1993; Neubauer et al., 1993 | 11 | 8.2 | 1.4 |
| de Carvalho et al., 1982 | 46 | 9.4 | 3.0 | |
| 8 | de Carvalho et al., 1982 | 46 | 9.1 | 2.5 |
| 9 | de Carvalho et al., 1982 | 46 | 9.0 | 3.1 |
| 10 | Jia et al., 2018 | 45 | 8.5 | 1.2 |
| de Carvalho et al., 1982 | 46 | 9.2 | 2.9 | |
| 11 | Neville et al., 1988 | 12 | 7.5 | 3.8 |
| Novotny & Mata, 1983 | 1 | 10 | NR | |
| de Carvalho et al., 1982 | 46 | 9.0 | 3.0 | |
| 12 | de Carvalho et al., 1982 | 46 | 9.0 | 3.1 |
| 13 | Novotny & Mata, 1983 | 1 | 11 | NR |
| de Carvalho et al., 1982 | 46 | 9.3 | 3.0 | |
| 14 | Ferris et al., 1993; Neubauer et al., 1993 | 11 | 8.4 | 2.6 |
| Hornell et al., 1999b | 430 | 7.8 | NR | |
| Howie et al., 1981 | 27 | 5.9 | 1.0 | |
| Novotny & Mata, 1983 | 2 | 8.5 | 0.7 | |
| de Carvalho et al., 1982 | 46 | 9.0 | 2.6 | |
| 22 | Neville et al., 1988 | 12 | 8.2 | 2.8 |
| 28 | Hornell et al., 1999 b | 395 | 7.6 | NR |
| Matheny & Picciano, 1986 | 37 | 7 | 1.6 | |
| Kent et al., 2013 | 52 | 7.6 | NR | |
| Quandt, 1986 | 62 | 7.2 | 1.7 | |
| 30 | Borschel et al., 1986 | 15 | 6.5 | 1.2 |
| Butte et al., 1990 | 10 | 7.2 | 1.6 | |
| Butte, Garza, Smith et al., 1984, Butte, Garza, Stuff et al., 1984 | 37 | 8.3 | 1.9 | |
| Pao et al., 1980 | 7 | 6.6 | 1.1 | |
| 42 | Hornell et al., 1999 b | NR | 7.4 | NR |
| 43 | Paul et al., 1988 | 20 | 6.1 | 1.0 |
| 45 | Novotny & Mata, 1983 | 2 | 10.5 | 3.5 |
| Neville et al., 1988 | 13 | 8.1 | 2.2 | |
| 56 | Hornell et al., 1999 b | 337 | 7.2 | NR |
| Matheny & Picciano, 1986 | 37 | 6 | 1.6 | |
| Quandt, 1986 | 48 | 7.1 | 1.6 | |
| 60 | Jia et al., 2018 | 25 | 8.3 | 1.0 |
| 61 | Borschel, Kirskey, & Hannemann, 1986 | 15 | 6.3 | 0.8 |
| Michaelsen et al., 1994 | 60 | 6.9 | 1.8 | |
| Butte, Garza, Smith et al., 1984, Butte, Garza, Stuff et al., 1984 | 40 | 7.2 | 1.9 | |
| 70 | Hornell et al., 1999 b | NR | 7 | NR |
| 72 | Novotny & Mata, 1983 | 1 | 8 | NR |
| 84 | Hornell et al., 1999 b | 290 | 6.9 | NR |
| Matheny & Picciano, 1986 | 47 | 5 | 1.7 | |
| 91 | Kent et al., 2013 | 52 | 6.6 | NR |
| Nommsen et al., 1991 | 58 | 6.7 | 1.5 | |
| Butte, Garza, Smith et al., 1984, Butte, Garza, Stuff et al., 1984 | 37 | 6.8 | 1.9 | |
| Pao et al., 1980 | 1 | 5.3 | NR | |
| 98 | Hornell et al., 1999 b | NR | 7.1 | NR |
| 102 | Novotny & Mata, 1983 | 2 | 7.5 | 2.1 |
| 105 | Neville et al., 1988 | 13 | 7.3 | 1.8 |
| 108 | Nielsen et al., 2011 b | 43 | 8 | NR |
| 112 | Hornell et al., 1999 b | 189 | 7.3 | NR |
| Cohen et al., 1994 | 50 | 13.8 | 3 | |
| 122 | Borschel et al., 1986 | 15 | 5.6 | 1.5 |
| Michaelsen et al., 1994 | 36 | 7.1 | 1.9 | |
| Butte et al., 1990 | 10 | 6.5 | 1.1 | |
| Butte, Garza, Smith et al., 1984, Butte, Garza, Stuff et al., 1984 | 41 | 6.7 | 1.8 | |
| 126 | Hornell et al., 1999 b | NR | 7.4 | NR |
| 140 | Hornell et al., 1999 b | 79 | 7.6 | NR |
| 147 | Cohen et al., 1994 | 50 | 13.1 | 2.7 |
| 154 | Hornell et al., 1999 b | NR | 7.8 | NR |
| 168 | Hornell et al., 1999 b | 20 | 7 | NR |
| 172 | Nielsen et al., 2011 b | 41 | 9 | NR |
| 182 | Hornell et al., 1999 b | 7 | 7.3 | NR |
| Cohen et al., 1994 | 50 | 13.6 | 1.8 | |
| 183 | Borschel et al., 1986 | 15 | 5.4 | 1.2 |
| Pao et al., 1980 | 1 | 7.3 | NR | |
| Partially breastfed term infants | ||||
| 201 | Paul et al., 1988 | 16 | 4.1 | 2.0 |
| 204 | Paul et al., 1988 | 21 | 4.0 | 1.7 |
| 210 | Howie et al., 1981 | 22 | 3.4 | 1.4 |
| 224 | Howie et al., 1981 | 21 | 3.2 | 1.3 |
| 234 | Paul et al., 1988 | 12 | 3.1 | 1.7 |
| 237 | Paul et al., 1988 | 18 | 3.2 | 2.1 |
| 238 | Howie et al., 1981 | 19 | 3.2 | 1.2 |
| 252 | Howie et al., 1981 | 17 | 3.0 | 1.3 |
| Martinez & Chavez, 1971 | 9 | 11.9 | 1.2 | |
| 262 | Martinez & Chavez, 1971 | 8 | 12.1 | 1.7 |
| 266 | Howie et al., 1981 | 15 | 2.9 | 1.5 |
| 270 | Amatayakul et al., 1999 | 26 | 10.7 | 3.9 |
| Amatayakul et al., 1999 | 26 | 11.1 | 2.8 | |
| 274 | Michaelsen et al., 1994 | 18 | 3.4 | 1.7 |
| Pao et al., 1980 | 3 | 5.3 | 0.9 | |
| Nommsen et al., 1991 | 28 | 5.6 | 1.7 | |
| 277 | Paul et al., 1988 | 12 | 2.5 | 2.5 |
| 280 | Howie et al., 1981 | 15 | 2.6 | 0.6 |
| 284 | van Steenbergen et al., 1991 | 77 | 15.0 | 1.6 |
| 286 | Paul et al., 1988 | 7 | 3.9 | 2.9 |
| 360 | Amatayakul et al., 1999 | 16 | 9.2 | 4.8 |
| Amatayakul et al., 1999 | 18 | 9.2 | 2.8 | |
| 365 | Nommsen et al., 1991 | 21 | 4.6 | 2.1 |
| 368 | van Steenbergen et al., 1991 | 77 | 14.4 | 2 |
| 390 | Martinez & Chavez, 1971 | 9 | 11.9 | 1.4 |
| 400 | Martinez & Chavez, 1971 | 8 | 10.8 | 1.9 |
| 541 | Martinez & Chavez, 1971 | 9 | 9.3 | 0.9 |
| 548 | Martinez & Chavez, 1971 | 8 | 10.1 | 0.8 |
| Exclusively and partially breastfed preterm infants | ||||
| 24 | Oras et al., 2015 b | 24 | 14 | NR |
| 24 | Oras et al., 2015 b | 16 | 12.5 | NR |
| 24 | Oras et al., 2015 b,c | 8 | 8.5 | NR |
| 113 | Oras et al., 2015 b | 23 | 10 | NR |
| 113 | Oras et al., 2015 b | 5 | 9 | NR |
| 113 | Oras et al., 2015 b,c | 15 | 6 | NR |
| 234 | Oras et al., 2015 b | 2 | 11.5 | NR |
| 234 | Oras et al., 2015 b,c | 20 | 5 | NR |
| 417 | Oras et al., 2015 b,c | 8 | 5.5 | NR |
Abbreviations: NR: not reported; PNA: postnatal age.
a
Age reported as weeks or months were converted into an approximate age in days (e.g., 2 weeks × 7 days/week = 14 days, 5 months × (365 days/12 months) = 152 days).
b
Median number of feeds per day. All other studies present mean number of feeds per day.
c
PBF data from preterm infants. All other feeding frequency data for preterm infants are presented for EBF.