| POS | Rank | Heat | BIB | ATHLETE | COUNTRY | RESULTS | 
|---|---|---|---|---|---|---|
| 1 | 1 | 2 | FRA | France U20 | 
 FRA                 | 
                43.82 Q WU20L | 
| 2 | 2 | 2 | USA | United States U20 | 
 USA                 | 
                44.31 Q SB | 
| 3 | 3 | 2 | POL | Poland U20 | 
 POL                 | 
                44.55 q NU20R | 
| 4 | 1 | 3 | GER | Germany U20 | 
 GER                 | 
                44.73 Q | 
| 5 | 2 | 3 | IRL | Ireland U20 | 
 IRL                 | 
                45.09 Q SB | 
| 6 | 1 | 1 | ESP | Spain U20 | 
 ESP                 | 
                45.10 Q NU20R | 
| 7 | 3 | 3 | AUS | Australia U20 | 
 AUS                 | 
                45.18 q SB | 
| 8 | 4 | 3 | ITA | Italy U20 | 
 ITA                 | 
                45.50 | 
| 9 | 4 | 2 | CAN | Canada U20 | 
 CAN                 | 
                45.89 SB | 
| 10 | 5 | 2 | THA | Thailand U20 | 
 THA                 | 
                45.89 | 
| 11 | 5 | 3 | RSA | South Africa U20 | 
 RSA                 | 
                45.98 SB | 
| 12 | 2 | 1 | ECU | Ecuador U20 | 
 ECU                 | 
                46.20 Q SB | 
| 1 | NED | Netherlands U20 | 
 NED                 | 
                DNF | ||
| 1 | CZE | Czech Republic U20 | 
 CZE                 | 
                DNF | ||
| 2 | GBR | Great Britain & NI U20 | 
 GBR                 | 
                DNF | ||
| 3 | NZL | New Zealand U20 | 
 NZL                 | 
                DQ R163.3(a) | ||
| 1 | JAM | Jamaica U20 | 
 JAM                 | 
                DQ R163.3(a) | ||
| 1 | TTO | Trinidad and Tobago U20 | 
 TTO                 | 
                DNS |